I just spent 2 1/2 hours proctoring PhD exam and figured out how to finish my book by the end of March. I will very slowly finish one Chapter in what is left of Sept. I only have a few lines to go, but I need to track down references, finish translations, and change everything to U of Chicago Style. Then I have another chapter to write in October, etc... I realized I was giving myself a month to do a very simple task (complete a chapter I had already written, really) so I condensed here, expanded there, and came up with a plan. I realize now I am pretty much done with a lot of it, despite my slacking in the summer.
If I don't follow the plan I still have to extra months in the school year to work. At this point it is important to concentrate on getting things in their final form, rather than working randomly on everything at once.
Proctoring forces me to sit still and get work done.