Magic Key Reservations Conundrum

My partner and I are first time Enchant key holders this year and are excited for a Halloween trip to the parks we just booked. I realized when booking our three days that it burned 3/4 of the reservations we can hold at once and am concerned that we won’t be able to get reservations for our next trip, which we are planning for Dec. 10-12. When those dates become available in September, we’ll still be holding our Halloween reservations and I fear the busy holiday season will see those December dates disappear quick. Haven’t bought flights or booked a hotel yet and I’m looking for either some reassurance we’ll still be able to get those days come the end of October, or someone to tell me there’s no chance in hell haha. Thanks!

TL;DR: already holding 3/4 usable reservation dates (end of October), hoping to book three more days in early December. What are my chances?