Ideally, having about a month to prepare would be great! But idk if that is going to be possible with the delays this year? But who knows! You guys could be hearing any day now.
I did not interview, so I'm not much help there. But I know that those who did interview were required to sign a confidentiality agreement, so I'm not sure what they are allowed to talk about. I don't know how they assign the slots, but the interviews are conducted from 8am to late afternoon, but your actual pass through I think should take about and hour maybe 1.5 hours. And they usually offer tours of the school by students after your interview that you can choose to go on.
I don't know that we are allowed to tell you how many station there are. There are at least 5, I'll tell you that much haha. Seems like everyone is staggered at like 15 minute intervals or so. And they come down and get you to start at station 1 when your time comes.