Someone correct me if I'm wrong.
Point availability for borrowing is based on the date of the reservation, not the date of your use year. So, assuming you are making a reservation for February 1, 2012 at your home resort....It is in your 2012 use year.
You can make that reservation at 11 months out (i.e. March 1, 2011).
At that time you can use:
banked 2011 points (you may need to bank them before making the reservation)
current 2012 points
borrowed 2013 points
emacek