If you read the long list of rules and such it says a park reservation will be made for your for Magic Kingdom, and should show in your plans something like 5-7 days before the event. I thankfully already had MK as my reserved park, arrive for my trip on my day and always do MK while I wait for my room to be ready (out of state AP, so always have to have a room). Since I'm on site I kinda pull from a different bucket, but I started to get worried when it showed full for the weekend even though I already have the one day reserved.