We were married on December 18, and though I love Christmas, I didn't want a "Christmas Wedding". The only hints of Christmas were the church decor & the red roses in the bouquets.
Have his party the weekend before or after his birthday. Make it themed toward his interests as he gets older, not using Christmas related things. Give him his own day of celebration.
I had a former co-worker whose birthday is December 24. Her parents made sure Christmas Eve was all about her birthday & December 25 was all about Christmas.