In late November to early December is the busy season of post office, because of the Christmas and New Year shopping. Based on the past experiences. The orders had been placed from Nov 25th to Dec 25th, and the package ship via "Air Mail" by Post Office. The customers may not be able to receive the orders before Christmas.
So we recommend that our customers try to buy Christmas gifts before November 25. And after November 25 we do not recommend "Free shipping" .
A. Registered Air Mail (China Post)