Disney usually releases their park hours about 60 days in advance. For example, hours for June were just released. So you will probably see something for September around July 1 (give or take a couple of days). They also release the EMH at this time, although sometimes these hours, as well as the regular park hours, parade times, etc can change somewhat as your dates approach.
The thing that stinks is that you can begin making PS at 90 days out, but you have to guess at the park hours until they are released.
Good luck with your planning and have a great trip!
Steve