When i used todo big displays on my house (always had the most sockets in my town
) i would start putting them up on november 17 (my birthday so ALWAYS had the day off work). There was a lot to put up so it took some time to get sourted so had to start early.
However i would NEVER EVER dream of flicking the switch (exept for occational testing) untill December 1st. IMO if you start celebrating Christmas too early you devalue it. (and would always switch them off on jan 6th and were 100% removed by the end of the following weekend).