Growing up, we always decorated on the last weekend of November.
For some reason though, my mom started decorating earlier every year after left home. Before she died it was the end of October.
As for me, I usually do it at the end of November but I probably won't be decorating ta all this year. There's no point. I will probably have to rip it all down by the middle of December since I will likely be moving to another country at that point.