I would suggest since you are doing one meal making a reservation. Depending on how busy the day is you could do it 60 days out if it's a holiday weekend, 30 if a busy weekend, a week out anyother time for the convinience of not having to possibly wait. But if it's not busy you can decide the day before or even the same day and call ahead and probably get the time you want.
Only two exceptions that you would want to do further out is Blue Bayou in DL, and Napa Rose 5* inside the Grand Californian Hotel.
For suggestion I go with the two above if you want a Disney experience, and the later if you want a superb experience.
If you want characters then Breakfast with Minnie and Friends at the Plaza Inn, which is in DL.