I just made our ADR's for May 19 - June 2 and could get everything I wanted when i wanted except for Breakfastasaurus. To get 1 table at 8:00 we had to go for a different day then we wanted. (We have a party of 7)
If you know what you want I would do them now since the Dining Plan makes everything book up faster. This is the earliest we have ever made our plans, but are glad we have them.