In Germany we have a tradition of "Sternsinger" which is when the local altar boys dress up as the three Wise Men and come around the houses in groups of four or five, singing songs, saying a little poem and blessing the house. This is why you see * C M B * and the year written on many doors. They come around on the Saturday nearest 6 January.
So, until they had been, we would keep our decorations up, light the fire and make the house festive and cosy and invite them in when they came as they would be traipsing around in the cold all morning.
Since COVID, they stay outside the house and sing their songs there. But I still wouldn't dream of taking the decorations down before 6 Jan. They only go up a couple of days before Christmas although Advent decorations have been up since the first of Advent, so we like to get a couple of weeks' joy out of them.
My sister's birthday is on 6 Jan, and when we were little our mother always kept the decorations up for her birthday, especially if she was having a party.
Can anyone remember the gaudy garlands and paper chains we used to hang on the ceiling - fashions have changed so much in Christmas decorations over the decades.