Yeah, if it's an online process for submitting their letters, it should be pretty much instantaneous from the time they click submit. I usually told my LOR writers that it was due 5-10 days before it actually was, but that was in case something bad happened last-minute with them, not thinking about processing time or anything. And I did ask them to be my references a couple months before the due dates. I think you should be fine saying end of November! Good luck!