M2 at Feinberg here - at least during my interview year, they told us they would get back to us in ~1 month after the interview date (for people who interviewed after the Octoberish date when med schools are allowed to release decisions) but I got my acceptance about 2 weeks after the interview. Anecdotally, it seemed like they were pretty fast for people that they accepted right away after the interview and slower to respond to people who were ultimately deferred to the end of the cycle (February/March) - BUT I wanna say like a third or half the class gets in after being initially deferred (including some of the most accomplished people I know) so it's definitely not a bad thing or anything. I think it's always good to interview early but I interviewed in January so if you decide to wait until November it's not like you'll be super late in the cycle or anything. Also this was all two years ago so things may have definitely changed!
Don't be too nervous about your Feinberg interview! Everyone here is super, super nice and focused on making sure you have a good time and like the school. I felt like the faculty interviews I had here were some of the chillest I had and the group interview sounds scary but it's really fun (and some people in my class actually met when they did their group interview together).
Feel free to message me if you (or anyone else) have any specific questions or anything