I've knocked past the 20,000 word mark and have actually not followed my own advice: I've not written the entire book as SFD (shitty first draft) but, because I know the story, have been shaping and reworking the first few chapters. I'm pleased with my output and pleased with what has come out of the woodwork (ha ha lol - paper comes from word... ok, I'll shuttup).
Anyway, Birthright is moving forward but this is going to be a massive task - the final book in the trilogy; the ending with all of the threads which I knitted into the first two books, tied up. I personally think this is going to be a BIG book.
Meanwhile, continue to tell all your friends and relatives about the series and, by the time it is as big as HP or Twilight, you can be smug and say: I was there from the start.