I mentioned the trip last night and he said he didn't realize it was a Thurs, Fri, Sat and that he'd have to take two days off as opposed to one. So, now he said he might not be able to go.

Forgive my naitivity, but if he was available to go when he thought he'd only need to take one day off, why don't you go ahead on Thursday and he catches up with you on Friday?