I had a similar question, if I can piggy back! I have an interview in a few weeks already, and am waiting to hear back from another university that is close the one I am interviewing at. The interview days are a couple days apart, and they are on the other side of the country from me. Anyway, would it be inappropriate to email the PoI/call the office now to ask about invites, as I am trying to book flights now if possible? I don't want to appear impatient or anything, especially if I end up on a wait list or something.