Art is the most beautiful deception of all. And although people try to incorporate the everyday events of life in it, we must hope that it will remain a deception lest it become a utilitarian thing, sad as a factory.
No matter what - rehearsed, under-rehearsed, over-rehearsed, doubts about rehearsing - the first gig is always the first gig, and you put on your little praying hat, batten down the hatch, and do what you do.