@talllady1958,
Some of previous comment provide advice on your first visit. I would like to add few more comments.

A 7:15 appointment is not unusual. You will be surprised how many people around that early.

I want to warn you there is lot of construction in Rochester. If your hotel is not in downtown area and has shuttle, use that option. Parking is available but difficult at this time. Give yourself plenty of time to arrive on time. See this web site for additional information: https://www.mayoclinic.org/rochester-construction

If you have not had your per-appointment phone call, it is to review allergies and prescriptions.

On portal, if there is any forms / questionnaires to fill out, I advise doing prior to appointment so do not have to do when you check-in.

You may also may want to check out: "How to make the most of your Mayo Clinic appointment." https://www.mayoclinic.org/patient-visitor-guide/how-to-make-the-most-of-your-appointment

Would you care to share what section your appoint is with.