We live in the southern part of Virginia and have 13 hens. We got them as spring peepers in March so this is their first winter. As of about 2 days ago all of our hens are laying.
Here's what we do: Light bulb on a timer. The timer is set to go on at 5am to 8am (giving an early start to the day before the natural light takes over), we let them out around noon, then the light goes back on at 5pm (just when it starts getting dark) at which time they return to the coop, get their night time snack, and then the timer shuts off at 8pm. I would say this fits in nicely with the amount of "daylight" stevetone mentioned above.
So we've basically chosen to extend the lighted hours a little at the beginning and end of the day instead of all at once. One reason for this is that the night light helps to draw our birds to the coop, which is especially helpful in the summer.. We have 3 Guineas as well, and they need all the help they can get.
I hope this was helpful. It is our first year as flocksters.
Good luck!