Pause.
They don't know where to begin.
"I didn't know you meant literally!"
Yes, literally. Know your opening. Know the first few sentences so well, you barely have to think. This saves wear and tear on your nerves, but allows you to improvise too!
Wait a minute. You just said "know your opening."
Yes, that's true. For it is only when we know our opening, that we can fully relax, release the distraction of where to start and possibly improvise a stronger opening. OR... just go with what you have. You decide.