As Christmas Day counts as the first day of Christmas,you should take note of the twelfth day,which is today.
The 5th January....this is the correct date you should take them down.
Then again some people like to take them down earlier than this,and some take them down at a later time.
We have always taken them down on the 5th Jan every year.....
Took mine down this morning, glad I got the right day, someone told me I was a day early. Looked like we had a green carpet by the time I dragged the tree outside!
They should be down BEFORE twelfth night...so you could even take them down in the daytime on the 6th Jan but they shouldn't be still up in the evening......