You have until January 31st, 2010 to bank the 2009 points into your 2010 UY. Once they are there, you have to use those 20 before May 31st, 2011.
Of course, you will still have 2010 points and if you don't need all of those, you can just use up the banked 2009 ones first, and then bank the 2010 points into 2011.