I think a fresh perspective from being out of school for a couple years can be a plus. Less likely to burn out. Less like to hold on to old study habits that don't serve in medical school. I tell everyone to meet with an academic advisor as soon as they get to school and your case is no exception. They can help you get a handle on what strategies are effective - active learning like Feynman, practice questions or anki - and what may not fly in medical school - passive strategies like re-reading, highlighting and taking copious notes. Also can help with logistical things, for example I had never heard of the Pomodoro method before I talked to the learning specialist at my school! Wish I'd known about it during MCAT prep.
Don't pre-study. It's impossible to know the breadth of the content in medical school. You may study too in-depth or not in-depth enough. Neither will be valuable and you won't know the right amount until you get to school and see the content. Pre-studying also increases risk of burnout.