Where do you want to make dining reservations? The hotel restaurants will take reservations, but the City Walk restaurants take priority seatings. And, some times during busy weeks, some of the CW restaurants, especially Margaritaville, will not take priority seatings -- they block them out for spring break, etc. I was able to make reservations at the hotel restaurants (The Kitchen, Mama Della's) 30 days in advance, although I don't think I needed to call that early.
For the City Walk restaurants, a good rule of thumb is to not show up to wait in line when the parks let out -- you'll have a good 2 hour wait, even with your room card for priority seating.