Looking at my PubIt sales from last year, December 25th was only only slightly better (about 50%) than December 24th, but December 26th was twice as good as December 25th. I think I even remember this exact same conversation on Christmas! "Hey, how come I'm not having a huge Christmas bump?"
I think you have to wait until everyone finishes dinner and goes home and crawls into bed with their new Kindle/iPad/what have you, before they start saying, "Okay, now what?"
My sales are holding pretty steady right now across the board, except my one Christmas-themed novella, which has been selling better than it was on the previous days.