I’d be surprised if it comes in the middle of winter. The Russians have cut off power to Ukraine in the past which seems more likely a starting point. I wouldn’t expect a large scale invasion at this point.
Russia should have learned from its former enemies about wars fought in that region in the dead of winter...especially if Ukraine puts up a stiffer than expected defense. It’s much harder to be on offense than defense in the dead of a Russian/Ukrainian winter. Russia might lob a few mininuke or some high explosive type emp devices to implode power grids in Ukraine then sit back, gambling the world won’t do anything more than bleet like “wedgied” sheep!