I know the b1 is the problem for you right now, but its good to think of all his options at the start and not just that one and see what you can do to beat out most of those options at the same time. To start a match a GL will do a few things, b1(hit comfirm to bnb trait up combo which is a fuckin problem, or block confirm into 2 which you should never let him get out if you block the b1), lift which can be punished easily on block(scrubby GL start a match with lift, remember that you dont need to respect the guy if he starts with lift), backdash to set up zoning, back jump on certain maps to grab the interactable or a jump in if they're ballzy/reading your backdash(or if its that one map where the interactable is in between you both at the start..hall of justice I think).
If the GL is confident in the matchup, and confident in his combos he will open with b1. You can punish this with a NJ anything into a full combo, but given the off chance that your guessed wrong(or he hits b1 too early and nothing comes out..trust me it still happens after thousands of games)then you are getting blown up by the lift on reaction. The best thing to do if you feel the GL will do anything but backdash to start is a backdash yourself, then blow him up when he does whatever he does(cause that shit aint hittin ya).
Now there are a few exceptions that a cheeky green bastard might pull out. If he jumps in on you and you dont punish be wary of the tick throw setups, and the every present 3LMcancel(or the extra cheeky fake 3 LM, but only the boldest of GL's will do this). He can also NJOR(the air ouas rocket), and that will set up is airOR groundOR zoning pressure, and will hit some people out of their backdash. He should only be expected to do someonething like that if he feels he can outzone you or he feels your normals will beat out his.
Hope that helps
