I would argue a "primary/spotlight IP" is best reserved for a late May/June announcement. IPs are meant to draw in the general public who may or may not be interested in HHN, especially in the winter/spring when they are planning summer trips. A secondary less popular IP, like Halloween, Chucky, or Haunting of Hill House, should be announced earlier in March/April (or in the case of Chucky in October) to get HHN fans to book sooner than later.