free dining is Aug 26th - Sept 22 this year. If your dates are 8/26 - 9/4 then your ok as long as resorts for those dates are still avalible.
Now if your asking if you can get free dining for all of your stay if you check in prior to the starting date, the answer is NO. If you check in 8/25 you wont get free dining even though it starts the next day. you can however get it the lenght of your stay if you checked in anyday within the promotion period including 9/22. (some people arriving before free dining starts do split stays to get it though which would require checking in and out on the day it starts 8/26)
so if you arrive 8/25 you have to check out then back in 8/26. If this is the case for you i would suggest doing a room only and starting your packae the next day.
Hope this answers your question