Puppies don't shed a lot, but once their adult coat is in, it is non-stop shedding. If that is going to be an issue for you, a German Shepherd may not be the right dog for your family.
GSDs can be wonderful family dogs, but it is important to get them from a good breeder that puts stable temperament and health as a priority. Too many GSDs are skittish, fearful, unsafe around little kids, because of poor breeding and a poor genetic background. You may get lucky and end up with a good one, but why take a chance when your children's welfare is at stake?
Bringing a puppy into a busy, chaotic household at Christmas time is not a good idea - A puppy will need a stable routine and some time to adapt to a new home. Many responsible breeders won't even sell pup's for the Holidays, holding on to them for an extra week or two until life settles into a more normal routine before the puppy goes to its new home.