you can only use the banked points in the use year in which they are banked. an example would be: my use year is from august 1st-july 31st, any points that i banked prior to july 31, 2005 would have to be used before july 31, 2006. so the first thing to find out is what period of time the points are banked for. you also have to remember that there is a cut-off date in your use year, after which you can only bank a portion of your points -50% to the next year, the remainder of the points you must use or lose in the current use year.
you can book a cruise as soon as the points are published to dvc members. once you become owner of the membership you can call member services and make a reservation. check out the dvc boards-they can offer great assistance.