I've recently decided to try out speedrunning the game, but I have one question about the rolling start rule. Am I allowed to start moving before the game says "go"? I'm just not sure since the rolling start time doesn't affect the actual time to complete the trial, but I just want to be safe to know if I can start moving or not.

Hello Cupped, if you do a rolling start you are allowed to move before "go" if its not due to mods. This is the case because the "go" doesnt mean anything of importance if rolling starts are permitted and an IGT is present.