In most cases, getting a puppy for a Christmas gift is a bad idea. A puppy is likely going to be a 15 year commitment, and it's certainly not an impulse buy.
* The weather in many parts of the world is cold! Puppies need many many trips outside to do their business. That's much more comfortable for you and the puppy if it's not freezing out. It's also better to choose a time of year when you have extra time and will be comfortable spending quality time waiting and playing with your pup outside.
* A puppy is not a toy, and sometimes small kids treat them like they are. It's best to separate the idea of "Christmas toys" and a "new puppy".
* The holiday season is chaotic enough without tossing s needy puppy into the mix. Puppies need a lot of your time and commitment. A new pup will either take away from your holiday fun or your new pup will in some way likely be a bit neglected with all the holiday bustle.