The cancelled Levi World Cup was in mid November, or second weekend of November, but a week later it would have been fine. Ruka Nordic Opening (world cup for Nordic skiing events) is held last weekend of November and has never been cancelled due to lack of snow. Wind has hindered some ski jumping competitions.
For a rule you could say that some of the slopes will be open late November, and a couple of km of cross country skiing trails with artificial or stored snow early November.
But! It's not a true winter season yet. Those trails and slopes are opened for eager amateurs and athletes who want to start their snow training as early as possible. For the rest of us (ok, I use the skiing trails also) it's not really a winter. Not much of natural snow.