Hello Stacey,
Memory Maker, is a wonderful addition to consider for your Walt Disney World vacation. It is like having your own personal photographer ready to capture every magical moment.
Upon your arrival, if you purchase Memory Maker, at the regular price, then any Disney PhotoPass photos linked to your Disney account, that have not expired, are included in your entitlement. However, if you purchased Memory Maker at the advanced price, then photos will not be included in your entitlement until 3 days AFTER your purchase date.
As a side note, when entering one of the Walt Disney World theme parks, be sure to pick up a map. Each map conveniently displays a camera on a tripod. Here you can find Disney PhotoPass Photographers readily available to take your picture, in several areas throughout the Walt Disney World theme parks. And don't forget to ask you Disney PhotoPass Photographer if they can do a Magic Shot, some magical moments may show up in your picture.
If I can be of any further pixie dusted assistance feel free to ask and don't forget to say, "MICKEY!"
Amy M*o*