My first high end client.

Don't sweat it!
The shop I work at P/T gets a lot of customers that are pro athletes.
I'm not going to name names but a certain former team member, that has a history of off field issues, comes in with his car all the time. He's a dick, we just do what he asks and take his money. There are others that come and are simply terrific. A.J. Green is probably one of the nicest guys I've ever dealt with, super polite and makes his kids mind when he's there.
I've come to learn these guys aren't above anyone. They fart, belch and crap just like everyone else and the higher they are, the further they fall. Be respectful, professional and above all, yourself.