When to set up the Christmas decorations?

When to set up the Christmas decorations? I suggest the 17th December, the day the ‘O’ antiphons begin and the liturgy turns to the Saviour’s birth.

A glorious example: Arvo Pärt. Magnificat Antiphonen: No. 1: O Weisheit. Estonian Philharmonic Chamber Choir, dir. Tönu Kaljuste.