How many gigs in do you stop changing your opening line just because you're nervous?

I keep seeing newer comics treat the first line like it has to solve the whole room: introduce you, prove you're funny, explain the premise and calm your nerves before anyone has even settled. Is it better to keep one simple opener for a while so you can actually learn how to deliver it, or keep testing different openings until one feels natural? I'm suspicious that constant rewriting can sometimes be nerves wearing a little writer's hat.