Don't think about it, just write. Hesitation will only slow you down, save that shit for the editing phase.
Very good point. I've written quite a few words today, and feel optimistic enough about them. I guess the point of making progress is enough, in terms of closing the gaps. When writing in chunks rather than as a whole it can definitely feel like a whole project will never feel completed. But this advice puts things into perspective and means a lot!