You don't say where you are. You can add your general location to your profile & this will help others to help you. You may think this is irrelevant to your question but I am in Australia & most of my layers are now moulting & off the lay. I specifically buy hens that will mature as my older girls stop laying to ensure I have a steady supply of eggs but not every hen will lay over the winter months & may wait to start laying to the spring. However if you are in the northern hemisphere the longer daylight hours now happening will help bring your girls onto the lay.
Signs to look for are large, bright red wattles & comb.
If you know how, check her vent, which should be moist & red.
There should be a 3 finger space between the hen's pelvic bones.
She may squat for you.
She will probably show interest in the nesting boxes
A lot of my girls go slightly nutty just before laying, running round clucking & in & out of the coop.