Now that Halloween is over, it will be full force in terms of stores selling their Christmas decorations. Many other bloggers have been reporting seeing them even earlier, as early as September and early October.
Personally, I don't have too much of a problem with seeing the decorations out early.
Most stores that sell Christmas decorations use the same space that they sell summer items such as gardening, fertilizer, etc. Those spaces typically involve a lot of floor space, as do Christmas. Halloween and Thanksgiving decorations typically wouldn't involve that much space, so rather than have to place filler (as well as tear down displays after a short time anyways, why not start putting stuff up early?).
I also don't mind it because I'll often take a look through the displays if I'm in a store for ideas on things that I might want to buy or need for decorating.
I rarely, if ever, buy anything during the earliest time of the displays. This doesn't have anything to do with the fact that the decorations are out ‘too' early, it's simply to do with the fact that you rarely see stores putting items on sale until it starts getting closer to Thanksgiving.
Here's my last reason that I don't think it's really too early to start putting stuff out: As I've waited to get things closer to Thanksgiving, I've had problems in the past finding items that I wanted to get. In prior years, searches for ‘popular' items such as LED lights often led to empty shelves. It's not too early to put stuff out if people are buying it!
I guess my advice, if you think it's too early for Christmas decorations, is simply to walk by them and pretend they don't exist!