In most cases units become available exactly 6 months prior to the first day of the desired occupancy period. As each unit becomes available Hyatt first goes to the "Reservation Wait List" and takes the first name at the top of the list. After the wait list is exhausted, the units are made available to all members. In many situations there are more names on the wait list than available units; therefore, it's not unusual that there are limited opportunities.
In order to get the unit/week you desire, place your name on a wait list(s) EARLY. I have done this for years and there has never been a time when I did not get my preferred resort/week.
If you want to book Christmas 2009, put your name on a wait list for the desired resort(s) very soon. Just keep in mind that if the request is filled 6-months prior (i.e. June 25, 2009) you must have sufficient points in CUP at the time the reservation is confirmed. If not, your name will remain on the list but Hyatt will go to the next person who has appropriate points.
Weeks with major holidays are in very high demand so that's always a challenge to get those weeks. Even more if you only have 1300 points it will be even more difficult as you will likely only have enough points for a studio during a high point week stay.