Use year means absolutely nothing at all except for one instance....if you ever have to cancel a reservation.
If you cancel a reservation the points are returned to your account. In DVC you can bank points to the next year if you're not going to use them. However, there are deadline dates for banking. After certain dates, you can only bank a smaller and smaller percentage of points, and eventually none at all. Banking deadlines are determined by your Use Year month.
Example 1: You have an April Use year. For April your 100% banking deadline is Sep 30th, your 50% deadline is Dec 31st, and your 25% deadline is Jan 31. After Jan 31 you may not bank any points.
An April use year runs Apr 1st through Feb 28th (or 29th) each year. You plan a vacation for Jan 2004. This date is in your 2003 use year (Apr 1, 2003 through Feb 29, 2004). Let's say you make a 180 point reservation for January, 2004, using your 2003 points, and bank the remaining 20 points into the next year, or your 2004 use year.
In October 2003 you find out you can't make the trip. You cancel the reservation. Your 180 points are returned to your 2003 use year. You would like to bank them, but you are in your 50% banking window (Oct 1st through Dec 31), which means the <b>cumulative</b> number of points you can have banked is 50% of your contract, or 100 points (1/2 of 200). You've already got 20 points banked, so may only bank an additional 80 points to complete the 100 point total. This leaves you with 100 points in your current use year which cannot be banked and must be used prior to the end of your use year, which in this case is Feb 29th, 2004. So somewhere between October 2003 (when you cancel) and Feb 2004, you must use those points or lose them.
Example #2: Exact same as above except your use year month is August. Banking windows for an August use year are 100% (Jan 31), 50% (April 30), 25% (May31).
You cancel your January 2004 reservation in October 2003. Your 180 points are returned. You are still in your 100% banking window (Aug 1st through Jan 31) so you bank all 180 points into your 2004 use year.
If you plan to vacation during the same time of year all the time, then a use year month shortly before your vacation dates is best if you ever have to cancel a reservation.
If you don't think you will ever be canceling reservations, then use year month means absolutely nothing except the date you receive your annual allotment of new points.
Final note, if you cancel at 31 days or less, it doesn't matter what use year month you have, these points are treated special and have additional restrictions on them.
Hope this helps