A small number of derm programs offer interviews before and right around 11/1 (look back at that link), so some programs do look at your application before that date and some most likely don't. A lot of them download before that date, but will download updates as well. Try to get things in as early as possible, but if you're holding out for a letter from a derm god, then it's probably worth it to have the letter in your app, even if it's around that time. You can go ahead and make a slot for it in ERAS and attach it to your applications before having the actual letter at your Dean's office.