^That's something you should figure out with your host (and it's likely you'll here from them tomorrow). Though, chances are that if you arrive at 9 AM, your host may not be awake
As far as I know, you'll meet up with your host depending on when they don't have class and such. If your host is busy for most of the day or something, it's possible that you'll meet up with one of their friends.
Also, I could be remembering wrong, but I'm pretty sure last year there was a room that prefrosh could drop off their luggage in and then pick it up when they were meeting with their host, I wouldn't worry too much about it.