According to our friends who were there Feb '07, they were doing it at 4pm - coming down the stairs, dancing in a circle with the kids & then signing autographs & posing for photos.
Just got back last night and the charcters did come out on Monday at 4pm and I had my picture taken with Mickey and Pluto.... the mean cat from pinocchio was there as well....
oh shame didn't know this but not that we had time to go back to hotel for 4. we found enough of them were around in the mornings by the dinning rooms. they change over every 20 mins so we saw a few before eating & then different ones after.