We don't have Carol singers here in Germany but the altar boys and girls from the Church come round on 6 January (or the nearest Saturday) to celebrate the three Kings.
This is a tradition which is carried out nationwide and each year they collect for a specific project, usually for other children in a third world zone.
So, as no one else has seen our decorations this Christmas yet, we shall definitely leave them up for the children to see on Saturday, when they come in the house in their costumes and with their incense.
I wouldn't dream of taking them down before 6 January anyway.