How long to try artificial lighting?

[Spartan22]

This is also my 3rd year w/ hens (layers) I only use incandescent 40 watt light in my 12x10 (10 ft high) coop in the morning on timer to turn on @6 am and off after 2 hours. So they get 12++ of daylight all together since it gets dark by 630ish here. I use the light from mid September to January to give my chickens a break for couple of months, but I normally have constant supply of eggs anyways my almost 3 year old hens are mostly molting right now for the first time while half of my 19 month olds are molting, my 3rd gens are all giving us our daily eggs supply.