12 months for the last minute stuff. EC's are pretty bad in college. My freshman and sophomore year I have like 250 hours in a housing org and like 100 as VP of my dorm. I didn't do anything my junior and senior year other than ~600 hours of research during my summers. I tended to treat school as being more important than everything else so I at least ended with a 3.86cGPA and 3.93sGPA.
And for reasons to go into medicine, I first became interested in high school when I blew out my elbow, which I have been dealing with the repercussions of for 5 years now. I did some shadowing in HS and some during college (like 15ish hours maybe, watched a 7 hour surgery, too) and then got lyme disease as a rising senior which I then struggled with for about 6 months, or most of my senior year.
I was interested in medicine, but didn't really get serious about it until a couple years ago. What I have been doing definitely has given me better insight into the field and confirmed my desire to go into medicine. I really like working as a scribe and the volunteering that I do is really cool, so I've noticed a pretty big difference in myself the past couple months even. I knew I wasn't ready to apply this or last cycle and that I wasn't mature enough so I am taking time off for that reason.
Edit: If it matters, I worked ~40-50 hours a week during my summers, usually nights, except for soph-->junior year.