It is the number of hours of light that determines laying. That is why in egg production farms they provide supplemental light to make the days seem longer to the hens.And season determines laying, right? But perhaps not as strongly as daylight determines moulting?
So because Ivy was a very late hatch, her laying is aseasonal. Does that seem right?
I'm very curious about these things.
Ivy's egg laying should follow the number of hours of daylight as well. Now new hens will lay with less daylight than more established hens.