The day before the DAT, I had planned on studying all day. I went to Kaplan and started working on problems. By about 2 p.m., I had been practicing brutal story problems for a couple of hours, and finally said, "Screw it!"
I went home and took the rest of the day off. I played Xbox, watched South Park, and had a good laugh. I wish I had spent more of that day relaxing, because it was probably the most helpful thing I could have done. You need a break every now and again!
The day of the DAT, I woke up a few hours early and started running through the PAT section in the Barron's book, mostly the angles. I think this may have helped get my mind in gear for the actual PAT that day, since I did fairly well. I didn't study for any other subject that morning either; I figured by that point it was a done deal.
Good luck! Hopefully all your prep will pay off.