Ken calls it “Embrace the Draft“, I am less nice about it. I call it “Embrace the Suck“, and the concept is to push past your natural tendency to over-criticize your efforts and stop writing. Instead of stopping, push onward. Finish the novel. Starting over is not going to make you a better writer. Doing what you said—when you said you would do it by—will.
A finished pile of crap is a monumental milestone. In a direct crap-to-crap comparison, the completed crap is better than your only a single chapter crap.
I’m overexaggerating, of course. Your work is not crap. Even if it is, the learning process of finishing a manuscript cannot be denied. Now you can go back and polish that sucker! Whatever you do, don’t. Stop. Writing.