It depends on when you last interview is. I had the last possible interview, and I think I finished at like 4:30 or something like that. I remember I caught a 5:15 shuttle to the airport. If you schedule an early flight, then just tell the Admissions Office so they can give you the early interview slots.
I loved Duke 😍 I'm expecting a rejection, but I still loved it. The people are nice, I like how the curriculum is set up, and the lecture hall is probably the nicest I have seen. The only thing I didn't like is that there are no dorms. But living in Durham is really cheap, so I guess it's not that big of a deal. Also, people seem to receive really awesome financial aid packages.