"If you order by this date, time, and one of these delivery methods, then you will get your order by Christmas."
Guaranteed Christmas delivery:
Parcel Post - Order by 9am EST on Wednesday, Dec 15
First Class Mail - Order by 9am EST on Monday, Dec 20
Priority Mail - Order by 9am EST on Tuesday, Dec 21
Please see the USPS Website for more details about the cut-off dates for International and APO orders.