How long before Sex should I wash my butt?

Hey everybody :) I guess you can read my question from the title. Im about to fly over to my boyfriend soon and the thing is that I'm arriving relatively late, so I'd prefer if I could get that done at home, like 4-5 hrs before my visit. Usually I'd do it right before sex, but after months of patient waiting that's kind of a downturner. Thanks for answers in advance!