There are lots of milestones to celebrate when crafting your novel, pretty much anything that's a multiple of one-thousand words is a good one.
Right now, I'm within striking distance of being able to say that MINIMAL is really, honest and truly a "novel," as I am currently sitting at ~43000 words. Soon, I hope, it will reach the much-coveted 50000 mark--which is the recognized standard for being a true "novel," by whomever it is that decides these sort of things.
What's funny is, I still have NO FREAKIN' CLUE how long a story it will be! This thing could hit 100000 before I'm done. I really don't know. It's an interesting journey, writing something like this. But as they say: so far, so good.