it DOES start at 11:45 am. It's a bit weird because a lot of the other schools start their interview day at 9am. But the difference with NOVA is that there's no presentation of their curriculum. your day basically starts with lunch with current students and then tour. and around 1pm you have your interview.
i was there way early because my hotel only offers shuttle at a certain time. but I would say if you arrive at 11:30 that would be fine