I figured it out
Called HGVC to find out. Apparently, on West 57th, I can only reserve during "Home Resort" time frame (9 months out). If I want to reserve in the "Home Week" time frame (12 months out), my home week (original purchase week) must be the Home Week time frame. In other words, if I want to reserve West 57th for next December, my registered week of purchase must be in the winter weeks. I guess I misunderstood my reservation rights.
As for Seaworld, there is no Home Resort time frame. I can reserve all the way through the "Club" time frame, but still limited in reserving for Home Week time frame unless my purchase was registered for the winter weeks.