This probably should be its own thread as this is a Fightcade client discussion thread. I’ll answer anyway:
You die. Heh. No seriously, Bison only has one reversal, his super. So if you don’t have a super stocked and you’re about to eat a command grab, you can ether attempt a reversal throw (assuming you aren’t out of throw range) or jump backwards and hope their command grab timing was off. If you are fighting someone who knows what they are doing and they catch you near a corner, you’re dead. That’s the nature of SF2 and playing Bison in general (Can’t jump out of command grabs and Bison has limited reversal options).
Practice dude. Get set up with a ST training mode somehow (MAME/HDR/Dreamcast) and start trying to find a feel for how fast you can get a charged move out. The more you practice, the easier it will be to get a feel on how much charge you need. Like second nature.