The points you bank can be used for trips from June 1, 2003 through May 31, 2004. When you can call to make the ressies follows the 11/7 month rule. Any points you bank have to be used by May 31, 2004 or they are lost....they can't be banked again. They also can't be borrowed back into this year.
However, if something came up and you did need points this year after you bank them, you can "borrow" from your June 2003 for reservations up until May 31, 2003.