It sometimes takes a while after they have completely regrown feathers before the hormones initiate body changes that allows ovulation and the ability to pass an egg.
It is important to increase light slowly. They don't respond by laying eggs like truning on a light switch. Chickens (and all animals) detect a gradual increasing of day length - or more accurately, day length in relation to length of darkness.
After their first autumn, no amount of light will keep them laying through the winter while they are still in the throes of recovering from molt. Feathers are 93% protein and they can't grow those while still kicking out an 6 gram lump of protein every day.
During this time the reproductive tract gets a much needed rest and rejuvenation.
Time change (daylight savings time) isn't detected by chickens because day length changes incrementally at about a minute or less a day. It doesn't change an hour when we set our clocks back or forward.
Where I live, days are now 16 minutes longer than they were at winter solstice.
What breed birds do you have? Have their combs and wattles started to enlarge and turn bright red? If not, you still have time to wait. Check the distance between the pointy pelvic bones. If there isn't 2+ finger width then they aren't ready.
I would cut back the day length to 10 hours and increment it gradually by about 15 minutes a couple times a week.
I imagine you are feeding a layer feed. I would switch to a grower or all flock feed that is 18-20% protein till you start getting eggs. The extra protein will help with recover from molt and they don't need the extra calcium now. Birds not building egg shells shouldn't be getting 4% calcium.
