If I were you, I'd take 15 minutes today and write a what if. While this might not be a fully new concept like it is for many of us, it can be where you'd take one of those unfinished outlines. The spirit of the Prep is to begin to get into a daily writing habit before November happens, and while you missed that in the rules you can still manage to put that together.

Tomorrow and every other day you can revisit what you've written, revise or rewrite for 15 minutes, and get into your daily writing habit that way. I know it helps me to have the writers around me trying to complete their tasks, and even if I finish early, I keep on working tasks every day (for who knows how long because that's just how I work) to be ready for that novel.