When you purchase new, you get "Current Year" points. Thus it depends on what use year month you buy.
For example, if you purchased a February use year, you would get 2008 points since the "current use year" for Feb goes 02/01/08 thru 01/31/09.
If you purchase an August use year, the 'current' year is 2007 since an August UY is currently within it's 2007 use year timeframe of 08/01/07 thru 07/31/08.
If you waited until Sep 2008 and purchased that same Aug Use Year, then you would get 'current' year points which would be 2008 points.
Normal banking deadlines are 8-months, so an August UY purchased today would get you Aug 2007 points which could be banked anytime before April 1st, 2008.
If you purchase a use year and are past the normal banking deadlines,
DVC does allow you to still bank those points at the time you purchase. For example if you purchased a June Use Year month, you would get June 2007 UY points. The last day to bank June UY points is Jan 31st, so you would be past your banking deadline. DVC would still allow you to bank those points.
Hope this helps