Hi, Rochelle!
You have a perfect plan!
While the calendars for September are not yet posted on each particular park's calendar page right now (but they will be shortly), you CAN find park hours for some September dates by looking at Walt Disney World.com's homepage, then selecting "Park Hours" from the list on the bottom left side of the screen.
I've provided your link to "Today's Park Hours" here, for easy access.
From there, you can use the calendar icon near the date to move to September 2012. There, you'll find all of the parks' hours, Extra Magic Hours, if applicable, and notes on refurbishments that are scheduled to take place at each park at that time. Keep in mind that these park hours are subject to change, though, so check back often as your vacation gets closer.
Should you wish for even more specific information, you can click on the park name right on that page, or by selecting the park from WDW's homepage as well, and clicking on "Calendar" there. Those monthly calendars have dates which are clickable, and will give you additional information such as parade times and nighttime spectaculars as well. Again, September may not yet be available on these more detailed pages, but at least you'll know where to find them when they are posted shortly.
Have a great time lining up the best combination of Dining Experiences with the park hours; I look forward to that more than some folks like the fun of a new crossword puzzle! Happy planning and come back for more help when needed!