Well, I did a little search for winter sowing Basil and Parsley, and I read that people in your zone have been winter sowing both just fine. However, my concern with Basil is that it is tender, so even though it sprouts, if you get a cold period, that could kill off the sprouts. Personally, I'm waiting until April to WS mine, but I'm also in a colder zone than you are.

Parsley I'm going to WS as soon as I get some soil.

As for Stocks, it was one of the first to germinate here, also zone 6 -north central Idaho-. It has managed to survive a week of lows as low as 17F and day temperatures not above freezing. My snaps were wintersown early too, but they are yet to sprout.

Stocks and snaps should be fine to sow now; basil (like LilBlossom said) is tender. I usually sow basil - and parsley - in late March to early April. They come up pretty quickly and grow fast. Last year I had the stuff coming out of my ears.

PV