OK, I just did an AKV add on. If you add on now, you will get 2008 points. If you are able to get Jambo points, they will be immediately usable. If there are no Jambo points available in your UY, you will get Kidani points. The Kidani points will be 2008 points, but they will not be usable until the 2009 use year. So you would bank the 2008 points. There would be no dues on the Kidani points for 2008 as they are not yet usable for reservations.
Hope that helps.