I'd say 60 days out and use the website to book reservation if you think you need to. However, much of it also depends on how busy the place is. We went at the end of August this past year, and our first afternoon, my DD called Bubba Gumps to make a reservation for later that night, they laughed at her and said none was needed. We walked into every restaurant that 5 days we were there (Tues-Sat the third week of August) with very little wait if at all. We went to Bubba's, Mythos (for lunch), NBA and Pastamore, and the Buffet place and were seated within minutes. Can't rave about any, all were more expensive than I would have liked, but all were close to our hotel (The Portofino) and a short break from the parks, as well as a convenience when you have hungry kids.