Not enough, unfortunately. I read everything Harvard mailed to me and practiced some possible interview questions.
What impressed you positively?
Everything. My host was amazing and both my interviewers were really cool.
What impressed you negatively?
All the construction going on near Vanderbilt Hall.
What did you wish you had known ahead of time?
I should have been more confident and known more specifically about the New Pathways curriculum. I also wished I had known just how much free time I would have between activities. (First interview: 10:00, second: 4:00)
What are your general comments?
Everything was great. I was really nervous duing the first interview but eased up enough to really enjoy the second.