The most important thing to consider when scheduling your interviews is NEVER LET ONE GO. The interview is the only time you get to show the admissions committee that you are more than just the papers you have submitted. It can help the admissions committee sway in your favor by showing them that you have one or more of the keys (passion, authenticity, or initiative).
You should not schedule multiple interviews in one day. You don’t want to be running from location to location or worry that an interview is going to take too long and prevent you from attending your next one. It is also mentally easier on yourself if you spread them out a little bit. You should also allow yourself plenty of time to get there and arrive a little bit early so you can calm down.
One little known trick is to schedule your less important interviews first. This allows you to get a little bit of a trial run for your top school’s interview and provides you a confidence boost. This is hard for early applicants to do, but you can sometimes schedule an interview for a state school application or a school with rolling admissions to get that practice interview in.