When I had a 'normal' life like most other people Christmas was a really big deal at our house. My daughter was little and loved it and looked forward to it like most little children.
I wrapped the lights on our artificial tree myself. The prelit trees don't have enough lights on them to suit me, and if one goes out it can be hard to replace it. Putting up the tree, just a 7' model with most of the lights already on it from the previous year, but usually having to replace lights on about 7 branches on average every year, it would take about 5-7 days just to put the tree up.
With 1800 lights on the tree and 550 ornaments (ours was an I Spy tree), I didn't want to put the tree up after all that time and work and then take it right back down a few days later. I wanted our family and friends to be able to enjoy our decorations a little longer.
Every room was decorated to varying degrees and we even had some trees that lit up outside at night. Christmas was a very special time for our family and given all that was involved with preparations -- not just decorations, but planning events and food, etc., I always started with the tree, putting it up in October. That way I could work just a few hours a day and not have to rush. Doing it that way actually took a little longer than 5-7 days.
We didn't generally start actually celebrating Christmas until Thanksgiving night, and then it was Christmas all the way to New Year's.
So I started putting the tree up early in October even before Halloween and if it was ready, we turned the lights on whatever day in the last half of October that the tree was finished. However we didn't start listening to Christmas music or watching Christmas movies until after Thanksgiving Day.
I think it all depends on the family as to when the celebrating begins. Before I had so many decorations to put up and so many events to plan for (hubby was a lawyer so we entertained more), I used to start decorating the tree on Thanksgiving night. I have known people who leave their decorations up all year around, because they love Christmas so much.
Another reason I started early was so that when the entertaining and community/church events were underway I had more time and energy to enjoy them instead of having to rush around. Planning ahead and getting everything done ahead that can be done ahead, makes for a more enjoyable Christmas season. Employing family members to help wherever possible makes it more joyful too.