Well, free dining is being offered during those dates, so availability is already pretty slim for that time frame. Walk ups are pretty tough during those times. Some places may be impossible to get in while others may have very long waits since everyone is trying to get the most out of their credits. You could wing it, but you might try and book a few things if you have anyplace you really want to dine and can find an opening. If you're on DDP, I'd book things just so you're not wasting any credits. Things do tend to open up if you watch the website in the last few weeks before travel.