How can I plan our ADRs if I don't know what parks will have EMHs? We won't have hoppers, but if we want evening EMH, we need to plan to be in that park all day.
The park schedules are now posted six months out. Since dining reservations can now be made 180 days out (plus 10 additional days for Disney resort guests) you should be fine.
Your other option is to eat at one of the Disney resorts, but make it one close to the theme park you plan on. It makes it so much easier travel wise.