Welcome to the Disney Parks Moms Panel, Darcy!
I can't think of a more wondEARful gift to give a Disney-loving family than 365 days of magic! As an Annual Passholder myself, I know well the value of such a pixie-dusted Christmas surprise.
The date at which your one-year of fun begins is the first day you use your new pass to enter a Walt Disney World® Resort Theme Park, this is the official "activation" date. However, your pass must be activated before you can select your customized Annual Passholder MagicBands - I know this makes it difficult to use the MagicBands as a gift for Christmas if you are not wanting your park entry benefits to start yet.
One suggestion I have to consider is to purchase MagicBands through the
Shop Disney website, or app, to use as the gift under the tree. This would allow you to give a MagicBand that is unique to each family member! You will still be able to link purchased MagicBands to each person via My Disney Experience. Then, when you add their Annual Passes, they will auto-magically link to that MagicBand. This way, you can wait to activate your passes until you're ready to start your yEAR of magic.
I hope this is helpful, Darcy! Please let me know if you have any additional questions. I'm here to help make your amazing gift as magical as possible while also helping you maximize your Passholder benefits.
Faith