In my family, the Christmas season does not start after Halloween. It doesn't even start after Thanksgiving.  We usually put the Christmas tree up 3-5 days before Christmas.  In our family and at my church, the period after Thanksgiving until Christmas is called "Advent."  This time is a period of planning and preparing for the birth of Christ Jesus.  It's a time to remember the great wonder that God the Father sent his son, Jesus, to earth.