You have 23-24k word stories?!? Uh, yeah, that's like literally half NaNos there. You should go back and apply these things to them. The official NaNo site also has a planning guide you can download for free. It's the "NaNo 101 Prep Handbook" listed here https://nanowrimo.org/nano-prep-101.

Good luck with all your stories! So exciting! Though remember that during the official NaNo, you're not supposed to be working to make things all pretty and perfect. WRITE! Make it better in December, January, etc. No editing "allowed."