Interviews occur at the end of the day (thankfully the day starts at 11:00, 10:00 if you do the housing tour, so you shouldn't be too tired). It occurs after the lunch and tour. You and everyone else in the interview group will meet in the same room that you gathered in during arrival. You're stationed there with 4-6 fourth year medical students who are there to answer your questions as well as assess you ("fishbowl"). I honestly would not stress out too much about this, if you have questions you'd like to ask then go ahead but if you don't have any, I wouldn't sweat it. I mostly listened to what others had to say and asked maybe 1-3 questions. Just make sure that you're not looking at your phone, sleeping, being rude, etc. One of these students will also act as your student interviewer. Depending on when your faculty interview is scheduled, one of the fourth years will let you know that they are your interviewer and will pull you aside for the student interview. This may be at the beginning of this "fishbowl" session or towards the end of it. Interviews are scheduled for 30-45 minutes but can go longer.
As for the interview itself. I would suggest that you go over your application and pay special attention to your responses to the JHU secondary questions. If you wrote about research, be able to explain it, if you discussed a specific experience be ready to go over it in detail. Be prepared for your interviewers to be familiar with your application and ask specific questions about your responses.
