Same as in your other decorations poll; I haven't voted yet. Would you care to add another possibility?
Traditionally people start decorating at or around the beginning of Advent (first Sunday of Advent). That's the last November weekend or first December weekend.
Some lights around the windows are put up then and maybe some window decorations made by kids. Christmas trees will follow much later (shortly before Christmas) and such things as figurines are not common here (although a certain type of Santa doll, hanging out of a window, has been becoming quite popular over the last years
).
In general, decorations are far, fare less than in the US.