Five weeks.
I had no faith... none of the lists I read listed parsley as a winter sowing candidate, and then, after I set the sown milk jug out on the patio, the temperatures plunged into the teens for days.
I chalked it up to a 'nothing ventured, nothing gained' experience. What a pleasant surprise!
Next year I'm winter sowing!
UPDATE:
The pleasant glow faded after my seedlings cooked on the really hot sunny day we experienced right after they sprouted. Next year, the north side of the house!