It was about an hour. I think we showed at at 6:30 thursday. They talked about benefits a little. They said all sorts of stuff to scare us into not getting hired. They took us around the building. We then could sign up for interviews the next day. So on friday I had my interview, and I got called on tuesday or so and they asked if I could start on monday, I said sure.
Also when they talk about the job they'll say stuff like the crappy shifts have more positions available than the good ones. That isn't true, they just want to get people to sign up for the crappy shifts. Decide what shift will work best for you, and sign up for that one, you'll get the job anyway (depending on the size of the hub or center), if they're doing a tour though it's probably a hub, so they'll likely have 4 shifts. I hear noon day (10AM-4PM or so) is pretty easy. Preload (3AM-8AM ish) is supposedly easy, but I wouldn't want to get up that early. Twilight (5-10PM) is a pain in the butt, but the hours are good. Midnight (10PM-3AM) is too late for me, and they probably process as many packages as twilight.
If your going to a center you'll likely have two choices, preload, and local (5PM-10PM), but it is harder to get a job at centers, because the guys there don't quit.