It is extremely variable. I did not get my first egg till my girls were 8 months of age, and even still, only two out of four are laying yet. The shortened days mean prolonged egg wait. generally, the rule is 21 weeks I believe, but don't be suprised if you don't get eggs till spring when the days are longer. I believe I read on this forum that a chicken needs 26 hours of daylight to produce an egg once they are of laying age.
I think you meant 16 hours, but anyhow..... Fingers on keyboards are funny things. No, they don't need 16 hours. Just an INCREASE from the low on December 21. There is usually plenty of light in late February and most breeders are very, very busy in February and March when the hours of daylight are often just 11 or 12 hours, but since it has increased so greatly from the solstice and since the sun has risen in arc in the horizon, it usually kicks the layers into a pretty high gear.