Well, there are PIN codes and there are "regular" codes. JMO but if you're looking for next Jan for a PIN code (tied to your name and address) I probably would wait to order my DVD until later in the year, just in case, for the reason you mention (dates might not be what you're looking for in 2009).
Otherwise, the "regular" codes that came out for last January started showing up around the October before, so maybe if you waited until about then to order you might have a better shot (though again, this is just a guess

) :
For check ins between 1/1/08-2/13/08 Annual Passholder room-only rates became available on 10/31/07, exp 2/13/08
For check ins between 1/1/08-3/15/08 package deal (discount + free ticket upgrades) for Canadian residents became available on 10/18/07, exp 12/15/07
For check ins between 1/1/08-3/15/08 package deal (discount + free ticket upgrades) for Disney Rewards® Visa® Cardholders became available on 10/29/07, exp 12/15/07
For check ins between 1/1/08-3/15/08 package deal (discount + free ticket upgrades) for general public became available on 11/1/07, exp 12/15/07
For check ins between 1/6/08-2/2/08 "Bounceback" room-only offer only for guests staying at WDW Resorts and willing to prebook their next vacation for selected dates in 2008 (at selected resorts only, and dates available vary by resort) became available on approximately 10/23/07
For check ins between 1/6/08-2/2/08 package discount for Disney Rewards® Visa® Cardholders for OKW and SSR only became available on 11/30/07, exp 12/29/07
For check ins between 1/6/08-2/2/08 room-only discount for Disney Rewards® Visa® Cardholders for OKW and SSR only became available on 11/30/07, exp 12/29/07
