You would need to get a room only reservation for the day/days before the FD promo starts. For example, if FD dates were starting Dec. 10th, and you were planning to arrive on the 8th, then you would do a room only reservation for the 8th and 9th, and book your package starting on the 10th. If you are planning to go to parks on the 8th or 9th, you would have to get tickets activated early at Guest Relations, since your tickets must be tied to your package. And of course you would pay OOP for your meals those first days.
And another point as I was just recently researching this - you cannot prebook Fastpasses 60 days out for 12/8 or 12/9.
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Expanding the above scenario. Say your dates are 12/8 - 12/15 and
free dining was avail with a 12/10 check in. Also imagine you want to go to the parks everyday.
Res #1
12/8 - 12/10
> Room Only
Or
> Ticketless Dining Package (In this option call Disney to book a room with dining plan but no tickets. This isn't available on the site to book but can be done over the phone. Note a dining package can't be added to a room only booking via Orbitz or a third party - Disney must be the vendor. Also you need to be wary of dining credits expiring at midnight on 12/10 from this Res #1 booking. They don't carry over to Res #2.)
Res #2
12/10 - 12/15
> Free dining package
Book room, free dining, and 8 day park hoppers or water park more. You usually have to add PH or water park to qualify for free dining. This may change, however.
Next Steps
> Since you want to use your park tickets from Res #2 early when you arrive on 12/8, a CM told me on the phone you must activate them outside the park or at Disney Springs. Same CM said you can't activate early at your resort.
Considerations
> If you book
DDP plan on both Reservations carefully monitor your dining credits. With the overlapping 12/10 date you may see the credits get misused - i.e. your Res #2 credits could mistakenly be used before your Res #1 credits are fully redeemed. Others said to get a print out of your credits from front desk to keep track.
> The CM suggested that you don't use online check in. That way at the check in desk you can request the same room for both Res #1 and Res #2 provided you book same resort & room type. CM said it was more likely when requested in person. She said you still have to check in and out even with the same room however - so the resort CM can activate and deactivate the bookings tied to your magic band properly.
> Also in the case both bookings have DDP, I think if you forego online check maybe there is a greater likelihood your Res #2 DDP credits wouldn't go live early since you are doing a "manual" check in.
> Because your tickets are in Res #2 which starts on 12/10,
MDE will not let you book advance Fastpasses 60 days out for 12/8 and 12/9. Accordingly, you can only secure same day FP+ For 12/8. However once your tickets are active, you can schedule 12/8 (same day) and also book 12/9 (one day early).
I just taught myself all this the other day with help of other DIS'ers.
I think that's all the considerations! Sure I forgot something lol it's so complex