Dont do it, they will go into a molt! I start to lessen the light on the timer when it corresponds to what I've been giving them. I usually change the timer to go on later as the daylight increases, until the daylight is equal to the time my lights are on. I decrease the light time accordingly until I can turn them off completely. If you suddenly turn your lights off, they will think is time to molt, and you don't want that.. Hens need 15 hours of daylight for laying well.
Ok I won't.