The answer is "maybe". The
free Dining Plan is part of a qualifying MYW package, which is offered with limited availability. So in essence, when it is offered, you'd have to have your reservation conceptually moved from the inventory it was originally booked from into the inventory allocated for free dining. Having a reservation already provides you no advantage in getting the free Dining Plan. You still have to call in at the right time, just like people who don't have a reservation already, and you may end up losing whatever discount you may be able to secure for your non-free dining reservation, now, because discounts are extremely limited with free dining. Also, you most likely will be required to purchase admission (even if you already have admission), so keep that in mind.
The point is that if you
aren't going to use the reservation if you don't get free dining, then you shouldn't bother making the reservation now. That's, of course, not the case in your situation: You indicated that you "will definitely book the
DDP for [your] trip"
anyway, so booking your trip now does make sense. Just keep an eye out for when free dining is offered and call in and have your reservation switched over.
