Tim was able to deduce Batman and Robin's identities because he recognized a move that Dick did in his Flying Graysons routine. So what if he wasn't at that show. Would he just never become robin?

@a_bomb12: Perhaps he would have become Robin under different circumstances.

In the new 52 he became (Red) Robin without seeing the flying Graysons.

Btw. his original Origin Story became problematic any way when it was retconned that Batman was just an Urban Legend for most people, since it was a contradiction to Tim seeing Batman and Robin in TV.