You can buy it at any time, however, for the pre purchase price of $149 you must buy 3 full days before any of your pictures will be included. You can still have pictures taken but you would have to buy each photo or download during that time period separately. So if you buy today for $149 your included pictures would start on Thursday. If you buy Memory Maker at full price for $199, all pictures are included from time of purchase. Keep in mind, a la carte downloads are about $15 each. It seems like paying $199 for all photos with unlimited downloads is your best value.