It is common for chicks born mid summer to not lay till days start getting longer.
Normally laying commences at around 20 weeks or so but as days shorten it inhibits the hormones that dictate sexual maturity.
It's important not to switch to layer feed till one gets the first egg. Better yet, don't switch till all birds are laying and offer oyster shell in a separate container for actively laying birds.
Feeding something in the neighborhood of 4% calcium is way too high for birds not laying and can cause kidney damage as well as other problems.
What are you feeding, what did you switch from and when did you do it?
What are you talking about with the hay. Chickens really don't eat hay much.