I think that Batman has been in operation for roughly 10-12 years now. That, to me, is the only way to explain all 4 Robins. and Hal Jordan must have been in operation before Superman as well. thats the only way to account for Kyle Rayner.
10 Years Ago: Batman begins operation in Gotham.
9 Years Ago: Hal Jordan becomes Green Lantern (???).
8 Years Ago: Dick Grayson becomes Robin.
7 Years Ago: Barbara Gordon becomes Batgirl (maybe?) Emerald Twilight/Kyle Rayner becomes Green Lantern (???)
6 Years Ago: Jason Todd becomes Robin. Dick Grayson becomes Nightwing. (Possibly some of the old adventures of Swamp Thing and John Constantine)
5 Years Ago: Debut of Superman, Hal Jordan returns to life (???). Formation of the Justice League. Jason Todd is Killed by the Joker. Tim Drake becomes Robin.
4 Years Ago:
3 Years Ago: Joker cripples Barbara Gordon. Sinestro Corps. War. Justice League fights Martian Manhunter (???) Jason Todd comes back to life (???)
2 Years Ago: Blackest Night. Dick Grayson takes over as Batman while Bruce is gone. Damian becomes Robin. Tim becomes Red Robin. Batwoman debuts.
1 Year Ago: Bruce returns and founds Batman Inc. Dick goes back to being Nightwing.
What do you guys think?