If you mean you have a June use year and bank the 2006 points into your 2007 use year, the banked poits would have to be used for a stay that occurs before June 1, 2008. In other words that last night the points could be used to pay for the stay woudl be May 31, 2008.
Doesn't matter when you call to make the reservation. Point usage goes by the date of your stay.
Best wishes -