Welcome to the Disney Parks Moms Panel, Jacquelyn!
I love that you're already planning ahead for next yEAR :) You are a guest after my own planning heart! Here is what I have done in the past, hopefully it will help you, too!
Since a
Disney Dining Plan can be added to your Magic Your Way Vacation Package at any time, as long as it's within three days of your arrival, I would hold off on adding the dining plan until you see if any special offers become available that include your travel dates. Once you know if your travel dates and Resort hotel are eligible, you can modify or rebook your reservation to reflect the available promotion. I totally understand the peace-of-mind that comes with having your vacation "on the books," so to speak - I'm all about the "book now, modify later" strategy. In fact, I booked accommodations just yesterday for Walt Disney World® Marathon Weekend to make sure I had something in place, with the hopes that when discounted room rates become available for January, I can modify.
I'd love to know where you are interested in staying, Jacquelyn. As you may know, the level of free Disney Dining Plan you receive is in direct correlation to the level of accommodations you book. For example, the 2017 promotion offered a free Quick-Service only dining plan with value and moderate level Resort hotels, and the deluxe and deluxe villa accommodations received the standard Disney Dining Plan, something to keep in mind as you begin planning.
I hope this helps! Please do not hesitate to reach back out to me with any additional questions you may have. I am here to help make your planning as "tasty" as possible.
Faith