Light is #1 but also nutrition, health, stress, etc..
A gradual increase in day length is better than abrupt. I started by adding an hour a couple days and then up it by 1/2 hour increments every few days.
I have light in 2 buildings starting at 5AM and then for an hour in the evening till 5:30. One has been running for about a month and they're all laying in there.
The other has been on for a bit over a week and I expect eggs in the next few days.
I had him switch to a higher protein pellet instead of crumbles. My hens haven't stopped laying. His coop and everything looks fantastic so all signs pointed to feed. I checked the pelvis spacing and o can only fit one finger between the bones so idk if they're stunted behind due to feed.