Hey sorry its wordy but its mostly hyperlinks to pictures for and easier read :P
(sorry in advance for typos)
According to Nightwing (NW) #0 it had been 5 years it and the events of NW#1. In NW#0 it does not specify is this means 5 years since his parents’ death, OR 5 years since he becomes (which is after months of training). In that time the only things we know for sure are that he was Batman at one point (NW#1: http://media.comicvine.com/uploads/12/120358/2576990-nightwing_1_thegroup_002.jpg), he has a Romantic history Barbara Gordan (Batgirl (BG)#3 / NW#4) and Starfire (Starfire Red Hood and the Outlaws (RH&O) #6: http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Nightwing-+-Starfire-flashback.jpg), and he has been replaced as Robin 3 times (Batman and Robin (B&R)#12: http://insidepulse.com/wp-content/uploads/2012/08/Batmans-Robins-DC-New-52.jpg). Becoming Batman could be in reference to the events after ‘Battle for Cowl’ or the events after ‘Knightfall’- or something else entirely.
As far as costume goes: He never wore shorts, his first appearance was- http://insidepulse.com/wp-content/uploads/2012/09/nightwing-000-18.jpg (NW#0); he did wear his blue 80s costume- http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Nightwing-+-Starfire-flashback.jpg (RH&O#6). However there is nothing to support that he wore his black costume with the blue stripe (http://images3.wikia.nocookie.net/__cb20090225203242/marvel_dc/images/f/fe/Nightwing_0002.jpg). Prior to becoming Batmen he had the same black and red costume that he is currently wearing (RH&O #6: http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Jason-Todd-+-Batman-+-Nightwing-flashback.jpg). In RH&O #6 we see that Jason got his suit with the red batlogo from Kori, who kept it from her relationship with Dick - http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Jason-Todd-+-Batman-+-Nightwing-flashback.jpg. My Theory is that this is what Dick Grayson wore under the cowl while he was Batman- thus explaining the batlogo (http://www.francescofrancavilla.com/gallery/images/batman_2009_01_low.jpg).
Did Dick Grayson ever lead the Teen Titans? There is nothing in the New 52 so suggest he lead a group by that name, however there is evidence to suggest something similar happened. In RH&O#6 Dick looks like he is leading a team with Starfire and Arsenal (http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Nightwing-+-Starfire-flashback.jpg). In RH&O#1 Roy mentions to Kori about former Titan teammates (http://tansyrr.com/tansywp/wp-content/uploads/2011/09/starfire.jpg), but she cannot recall do to some unexplained memory loss. It is my theory that Dick Grayson lead a team of young heroes as Nightwing, but they were not called the ‘Teen Titans’.
CONTINUITY PROBLEM- Roy mentions Garth and Gar presumably reefing to Beast Boy and Aqualad (RH&O: http://tansyrr.com/tansywp/wp-content/uploads/2011/09/starfire.jpg). Beast Boy is still only a kid in by Teen Titans (TT) #8 with no prior superhero experience and this runs at the same time line as NW and RH&O (according to ‘Night of Owls’). Meanwhile Aqualad ‘Garth’ has just recently been mentioned in passing Aquaman (AM) 14 (http://media.comicvine.com/uploads/13/134757/2715855-aquaman.jpg) as a boy. Justice League (JL) #7 also happened at the same time as the ‘Night of Owls’ (http://3.bp.blogspot.com/-K4SeBYU-cdM/T9Yp21Lw3FI/AAAAAAAAA6g/5ADtAAWAQjI/s1600/owls2.png), and given the upcoming crossover AM also happen at the same time. Meaning that RH&O made reference to 2 characters who didn’t even exist- let alone have history with them [Somewhat troubling considering Scott Lobdell wrote RH&O#1 and introduce Beast Boy in TT#8]. If someone else can find a solution to this, that would be great...
So to some up so far Dick’s parents have died, and he has become Robin. Then he is fired/quits being Robin and leads his own super team, while Batman replaces him with Jason Todd. When Jason and Dick do meet they do NOT get along at all (http://insidepulse.com/wp-content/uploads/2012/04/Red-Hoods-and-the-Outlaws-6-Jason-Todd-+-Nightwing-flashback.jpg). Given the previous picture it looks like Dick was just about grown up when Jason took over. According to RH&O#0 the Joker played a hand in having Jason become Robin (http://cdn.ifanboy.com/wp-content/uploads/2012/10/Red-Hood-and-the-Outlaws-0-2012.jpg ). After becoming Robin he was killed by the Joker (‘A Death in the Family’), and resurrected by Ra's al Ghul, and his Daughter Talia brought him to the Temple of All to train. Next he returned to Gotham to seek vengeance on the Joker and Batman, after what I can only presume was a huge growth-spurt. It is also implied in RH&O#1 that he had fought with Nightwing often after this point (http://2.bp.blogspot.com/-bV1xktCrbLU/TojULUdyukI/AAAAAAAABao/cVS6ghdUYew/s1600/Starfire+in+a+bikini+red+hood.jpg). This sounds similar to what happened in ‘Battle for Cowl’ (http://images.wikia.com/marvel_dc/images/1/14/Dick_beats_jason_BTFC.jpg ) and the events of Grant Morrison’s ‘Batman and Robin’ from before ‘the new 52’ (http://media.tumblr.com/tumblr_llcfsyrdWy1qbujox.jpg ). However this does not confirm that ‘Battle for Cowl’ happened, it could refer to other encounters with Nightwing. This is all supposed to happed in a five year period, and Jason’s half of the story doesn’t even start until Dick is fired/quits- which is at least a year.
Hair: Prior to ‘Crisis on Infinite Earths’ he was a redhead (http://images2.wikia.nocookie.net/__cb20100611133952/marvel_dc/images/2/21/Precrisis_jay.jpg ). After this he was a brunette as soon as he met Batman (http://4.bp.blogspot.com/_Zgdcd7oA5OY/SeY-C8_EX-I/AAAAAAAAAiU/yBbjPD0NbSw/s400/peru21-jason-todd.jpg ). After ‘Final Crisis’ he claims he was a redhead but Batman always made him dye his hair to be more like Dick (http://i34.photobucket.com/albums/d134/per1etwo/comics/p2_bnr05_p15.jpg ). Now in the ‘New 52’ he’s a brunette again- unless he’s still dyeing his hair for no reason at all. He no longer has a white strip of hair from being resurrected by the Lazareth, but could that just be dye? I don’t think it is.
In TT#1 I see that Tim had been Batman’s sidekick at some point. It is implied that he is the one in hte picture with batman. (bottom right: http://cdn1.sciencefiction.com/wp-content/uploads/2011/10/Teen-Titans-New-52-Splash-Page.jpg) . However based off of his look what you started comment, it is unclear if he means himself, Bruce or Dick. Is it possible that this is Dick Grayson in the picture and he is wondering what Dick Grayson- the first Robin and presumably the first teen hero – was thinking? I feel this is unlikely
In TT#0 we find out that Tim was never Robin. Does this mean he was never batman’s sidekick either? My theory is that he was never called ‘Robin’ (out of respect for Jason) and always referred to as ‘Red Robin’. This explains why his costume in this photo is all red while his predecessors wore almost the same costume (Dick: http://insidepulse.com/wp-content/uploads/2012/09/nightwing-000-18.jpg; Jason: http://insidepulse.com/wp-content/uploads/2012/09/Red-Hood-and-the-Outlaws-0-Jason-Robin-2.jpg).
In RH&O#8 it looks as though Tim and Jason are on good terms (http://i11.photobucket.com/albums/a188/aubreys_master/Other%20pics/rho82.jpg). Tim also makes reference here to events similar to what happened prior to Flashpoint and the New 52 (http://images1.wikia.nocookie.net/__cb20060207211460/marvel_dc/images/6/65/Teen_Titans_v.3_29.jpg)
In B&R#1 Damian Wayne is approximately 8 -10 years old, which is the age Dick Grayson was when he was first brought into comics as Robin in 1940. Many people have taken issue with DC’s 5 year later idea. They mentions that if Talia and Bruce conceived him while Bruce was Batman, then Damiann should only be 5 years old since Bruce has only been Batman for 5 years. This is a valid point and a problem. As http://25.media.tumblr.com/tumblr_ma58tovVG41qhmpzqo1_500.jpg . By JL#1 Batman has become a myth/legend and humors of him have spread to Coast City (JL#1: http://media.comicvine.com/uploads/0/40/2075187-jlbatgl.jpg ). It is not unreasonable to think that Bruce may have been roaming the streets of Gotham as Batman for 3-5 years prior to JL#1 in order for rumors of him to spread around the nation. If his affair with Talia happened at the beginning of his career (let us assume it does) then we can say that it happened 3-5 years before JL#1 and thus 8-10 years before B&R#1, making Damian 8-10 years old.points out Damien was/could be a test-tube baby and his aging could have been accelerated. This is not a bad idea, and frankly resolves a lot of issues for me. However, mytheory is that Batman has been around for more than 5 years. He would have to. Otherwise Bruce returns home after years of being missing, becomes batman and meets Dick Grayson all in the same month. This is possible, but highly unlikely so I will dismiss any claim that Detective Comics #0 happened only 5 years prior to current events such as ‘Night of Owls’. JL, after #7, and B&R take place at the same time. Thus JL#1 is 5 years prior to B&R#1 and Damian (had he aged naturally) would have been 3-5 years old. Assuming B&R#0 is part of DC’s ‘5 years ago’ plan then Damien would have been 3-5 years old at this point-
So... are we pretending this didn't happen? Does this mean Tim's never had a girlfriend?