Seems to be in the morning, around 9am or so. The daily deals will change every day, and the weekend deals go up Friday, I think. When they have free shipping deals, they usually bump their prices a bit. You have to catch it at the right time. I am looking forward to their holiday deals though. Shipping time seems to be up. Regular orders are taking over 2 weeks to get to me. Built uppers are longer. My lowers took 17 days. I'm in no rush, but some people are. All in all, I'm happy with PSA.
I just bought a PSA upper on the 5th and it's scheduled for delivery on the 18th. So almost two weeks which isn't bad for them.