Odd, I haven't really seen much of Christmas preparations here yet. Ok there are more kid's toy commercials on TV all of a sudden, but apart from that... I don't yet hear any Xmas jingles in supermarkets, malls are not yet decorated with Xmas crap as far as I can tell etc...
The Xmas street in Helsinki will be opened in the very beginning of December I think, and generally I expect all the Xmas pushing to start in full force after the Finnish Independence Day, which is on 6th of December.
One thing I dislike in the weeks before Christmas that our work canteens tend to offer more and more traditional Finnish Christmas food. Thanks, but I get enough of that during the actual Chistmas days at home, I wouldn't want to eat the same stuff weeks beforehand. It is not that tasty food anyway, but I'll endure it during Christmas.
https://en.wikipedia.org/wiki/Joulup%C3%B6yt%C3%A4