@myhappyplace, this is from years of experience with Bounceback offers. If Disney continues with their same pattern for 2017, this is what to expect ~
Resort Guests who vacation in November & December will have a room discount offer for various dates in 2017. The percentage will depend on the level of resort booked for the bounceback (usually 15-20% for values and moderates, 25-30% for deluxe). You do not have to book a room at the same resort level you are currently staying at. Resort Guests who vacation in January though July receive the same room discount offer for the current year (2017). Resort Guests who vacation in August through October will have a free dining bounceback offer, for limited weeks in 2018.
Additionally, rooms for these offers are limited and certain room categories may be excluded (usually the cheaper views.) While free dining is valid for your entire stay even if your vacation begins on the last day of the offer, room discounts are valid only for the days in the promotion period.
For 2016, the room discount bounceback offer excluded the months of October and November; most of March and December; all holiday periods (MLK, Presidents Day, Easter, Memorial day, Labor Day) and various weekends throughout the year.
When you are there in December, you might be able to book a bounceback offer for your May trip, as most of May is usually included. The offer will be in the info packet in your room. You just dial ext. 8844 from your room to book the bounceback.