Starting over - when I bought VWL I told them it would be used for Christmas and was told then that Dec was the best UY. I assumed that was b/c it would be home resort and I could begin booking 11 months out since the rooms at Christmas may not be available at the 7 month window.
Is that part at least right? If not, how does the 11/7 month windows work?
No, your assumption was not correct.
#1: Use year has absolutely nothing to do with when you can book a vacation. Use Year ONLY determines which 'year' the vacation points will come from for that vacation.
#2: You reserve at your home resort up to 11 months in advance of your check-out date for the desired reservation. This is true no matter what your Use Year month.
#3: You may reserve at any non-home resort at 7 months or less in advance of your check-out date. It makes no difference of what home resort you own, or what your use year month is.
#4: Use Year can be important in the event you may ever have to cancel a reservation. This is because when you cancel, it can occur that your points that are returned could be late in their use year, and therefore not eligible to be banked. This could be a problem. Again, this can occur ONLY in the event of a cancellation. If you don't cancel reservations, this is a non-issue.
When your guide said Dec was the best use year for Christmas, it may because of this cancellation issue. With a Dec UY, if you have to cancel a Dec reservation, you still have basically 12 months to use (or bank) those returned points.
Examples:
John owns VWL. He can make a reservation today for Christmas 2007 since it's less than 11-months away. It makes absolutely no difference what use year month he has.
Bill owns OKW. He can make a reservation at 7-months for Christmas 2007. It makes no difference what Use Year month he owns.
For December 2007 reservations, ALL owners of ANY Use Year month would be in their 2007 Use Year, so all would be using 2007 UY points.
However, for other months, Members could be using points from different use years.
Example: John owns VWL, March UY. Bill owns VWL Sep UY. Both want to make a reservation for June 2008. Since this is a home resort for both members, they each can call July 2007 to make the reservation at the 11-month window. However John would be using his 2008 UY points because his 2008 Use Year goes from March 1, 2008 thru Feb 28, 2009, which includes his desired June 2008 reservation.
Bill on the other hand would be using his 2007 Use Year points because his 2007 use year covers the dates Sep 1, 2007 thru Aug 31, 2008, which includes his desired June 2008 reservation.
Hope this helps.