Here is a banking chart. If you look at December UY it says that you must either bank your points by July 31st or the points will expire November 30th. For example, January through November 30, 2017 is still in your 2016 UY, December 1, 2017 is in your 2017 UY. The only way you could use 2016 points for a December 1, 2017 reservation is to use 2017 points or bank by July 31, 2017 the number of 2016 points you need for the December 1, 2017 reservation.
BTW, you cannot make one reservation that covers two UYs. You need to make two, one through November 30th and another for December 1, 2017 and have MS link them.