In the Christian tradition the Christmas season is a period beginning on Christmas Day (December 25). In some churches (e.g. the Anglican Communion) the season continues until the day before the Epiphany, which is celebrated either on January 6 or on the Sunday between January 2 and 8… From Wikipedia
So if you keep your tree and other decorations up until the first part of January you are OK. Enjoy the season, all 12 days of it.