You gotta do all the ISOMETRIC stretching exercises in during the daytime several hours before the show and then after you setup the gear do a review of them again. Do the steering wheel exercise on the way to the gig. RIght before the gig standing backstage and everyone talking to you making you lose your concentration just do a 4 finger chromatioc note pattern justy on 4 frets(no brainer no thinking) over and over again - that way you can be polite and answer questions from the public and still warm up.