In our country, you can hear them as soon as September starts as a sort of herald that Christmas is on the way. (I am not sure if other people see it this way in our place but I think some people these days here hope for Christmas as soon as September starts because you look forward to the festivities and the financial bonuses and vacations that comes with the holidays) Christmas music will not be played as often through October to November. By December, you would hear it more often. What would start in December are children carolling on the door.