December 12 is a great end goal but you want to look out for losing steam. Unlike neurotypicals who are capable of… doing things simply because they want to do it, ADHDers don’t have that sort of inner motivation. Not in that way, at least. Wanting to isn’t (always) enough.
We need a lot of external motivation to keep us moving when the hyperfocus isn’t kicking in. If you want to use deadlines, I strongly suggest trying to break it up into a series of short deadlines. Again, December 12 is a great end goal, but smaller parts in between will help with feeling accomplished and like you’re actually getting something done.
And if you really want to, you can set small goals for yourself with the smaller deadlines. Like a word count you want to reach. Or setting a timer for how long you want to write a day. (But keep it short. 15 minutes of nonstop writing and then a 5-minute break, and you get to decide how long you want to do that).
I’d use the reward system as well! Reward yourself after you complete a writing goal. Whether that be reading a book you want to read, or watching a show you want to watch, etc. It can literally be anything so long as it’s something you like and something that makes you happy.
It depends entirely on how things work for you as well, though. See, I love trying new things and organizing stuff down to the detail, but using the same methods for too long tends to start feeling repetitive and boring, and the fun of it gets lost. So, unless it doesn’t bother you to do the same things, I’d try switching stuff up every once in a while. Make some deadlines shorter, break them up even more if you want to, etc.
Another thing I love using is a soft deadline and a hard deadline.
I struggle big time with self-discipline and tend not to complete something if I feel like I have to do it, so when I want to get something done I set a soft deadline. It basically is just the deadline I want to reach, but there’s no pressure to do so. I want to get something done by then, but if I don’t, it’s not a huge deal and I’m not going to be mad or upset at myself for not doing it.
But a hard deadline is basically a deadline I’m going to meet no matter what. I let the pressure guide me and push myself to just get it finished, even if it ends up being sloppy in the end. Since, you know, that’s the beauty of first drafts — they don’t have to be good. You can always go back and change it up or fix it if you need to. It just needs to be finished.