Hi Holli!
I can understand waiting to see if Disney offers free dining again this fall; it's a great promotion and is very popular. However, you don't have to wait. You can book a vacation package now and then if free dining is announced, you can call and have that applied to your package. An Authorized Disney Vacation Planner is great at doing that if you don't want to worry about looking to see if a discount has been released yourself.
This also would apply to any other discount released, though you can only take advantage of one discount. You should think of discounted rates as a "clearance sale". Disney is generally releasing the discount in an attempt to get more guests into the resort hotels during a specific time period. If you want the discount, you have to be willing to take what's available. The more flexible you are with the dates and the hotel, the more success you will have. There have been times when a substantial discount was released for the period we were traveling, but we couldn't take advantage of it because we had our heart set on a particular resort.
By the way, I think you are making a fabulous choice by staying at the Wilderness Lodge. It is my absolute favorite place to stay at Walt Disney World. Be sure to make an Advanced Dining Reservation for the
Whispering Canyon Cafe, and any other Table Service restaurants you are interested in. Reservations can be made 180 days in advance and you should definitely make them. While the parks will not be particularly busy because most children will be in school, the fall is a busy time for the Table Service restaurants in Walt Disney World because people make reservations in anticipation of a free dining promotion. Last minute reservations in the fall are very hard to get.
Enjoy planning and write back if you have any more questions!