Honestly tree has been up for about a week already. Refuse to do anything before Remembrance day though so the 12th would be the absolute earliest we ever even consider doing anything. ... Programmable lights have been up since we moved in though... install those mid summer on a ladder that isn't slippery and dangerous and just change the color as needed for the holiday. Orange for Halloween etc.
Edit: Side note technically 12 days of Christmas is the span after Christmas day not before. So following that logic decorate on the 25th?