Eating at Disney today is nothing like it was a few years ago. We used to be able to wait until the day of to make ADR's (then called PS's) when we went during the non-peak time. That's hardly true anymore. We're going the week after Thanksgiving (a non-peak time) and called a few days after the 180 mark and had to change a few of the times we wanted to eat by a few hours. I can't imagine if we waited until it got closer. From my understanding, Disney restaurants used to only book up 50% of their restaurant with ADR's and left the other 50% open to walk ups. I've heard from a few restaurant managers that that is no longer the case. That they allow 100% ADR bookings and if all of the time slots are filled they don't allow walk ups all day or if they have a few left open at a certain time then they will accept walk ups at that time.