We always taken them down withing 12 days of christmas day. They get put up whenever the parents have a spare weekend off work.
There is a house near where I used to live that puts them up at the start of October every year & they get mentioned on local radio. They have hundreds of decorations & outside there are thousands of lightbulbs. God knows what their electricity bill must be like. They let people in & look around too if they are interested. They started doing it years & years ago when they were told that a family member wasn't going to survive until christmas & so they had chritmas early.
Done it every year since.
There are 3 houses on our street with decorations up already.