All you office workers, truck drivers, and construction people, enjoy the holiday. All you writers, I hope your brain allows some rest, but don't count on it.
It's more likely that your fertile (shall I say, febrile?) brain will choose this purported "down time" to hit you with the best subplot ever, a great character quirk, or even a whole new book idea. And you know from experience that if you don't write it down...
That's the problem with creativity; it has a mind of it own. It's your mind, but it doesn't follow your rules. It will be hard to finish that special salad or remember the details of the place settings you planned while it whispers, "We could iron out that plot-knot in just half an hour." Of course half an hour would stretch to three, and then where would Thanksgiving dinner come from?
Nine-to-fivers, second shifters, even time-and-a-halfers know when they're done. Writers? It's never going to happen, so just accept it. There is no holiday from thinking, and that's our trade. So Happy Thanksgiving, and just be thankful if you can leave that WIP alone for MOST of the day.