Well, they do need a certain amount to stimulate the pineal gland.
12 hours would be minimum and no more than 16 because they also need the dark period of 8.
And yet mine lay in the middle of winter with only 10 hours of daylight. I'm not going to cull them for having a defective pineal gland.

One advantage of having a longer day is that they have more time to eat so they may eat more. That may give them a boost in nutrition they can use for laying eggs instead of just staying warm.
Another one is that light is a trigger to release a yolk to start the next egg. Since it normally takes more than 24 hours for most hens to lay that egg, they gradually get later in the day. Reduced light gives them less time to lay that egg so they will probably skip more days so you get a drop in production.
In upstate NY the OP will have something like 9 hours of daylight at the winter Solstice, 9 hours of dark in June. That means by the time the Equinox gets here so you have 12 hour days they will already have lost 3 hours of daylight. Will that be enough to trigger a molt? I can think of someone in Pennsylvania that it seems to from her posts. That's one of the challenges in knowing when to start and how long to make the day. 12 hours is probably worth trying, starting at the Equinox.