If it's somewhere that you really want, make the adr. Otherwise go with the flow, there are plenty of good places to eat at Disney and I'm sure that you will always find something to meet your needs and wishes the day of your trip.
I called last night and I got an adr for the Rose and Crown for Sunday night Jan. 29 at 7:30, no problem. I made this one so that we can see illuminations from the deck. Everything else for this trip is going to be spontanious.
Last October when I was there we never had an adr booked and were able to get into all of the restaurants that we wanted to (Yachtsman, Flying Fish, Chefs de France, and Rose and Crown) by calling the day of. LeCellier seems to book up early because of the dining plan (it's a steak house that only charges 1 credit instead of 2 at the other nicer restaurants). Enjoy and don't worry too much.