Are there signs that a hen may be laying?
If you are looking for visual signs that your young pullet is getting ready to come into lay, those might include the fact that her comb will get larger and redder right before she begins, and she will begin to "squat" submissively when you reach down to pet her. Additionally, she may get a little louder right before she begins, since she is experiencing new instincts, and she may not be sure exactly what they are telling her to do, yet. She may go in and out of nest boxes looking for a safe place, and she may try to drive the other hens away from possible egg depositories if she is feeling protective. After she gets used to the process, things will go more smoothly and she will be less irritable.
If you're just looking for signs that will help to separate a good layer from a hen who is not currently laying (like a broody hen or a hen that needs medical attention), again, the redness of the comb and wattles is helpful to gauge. Comparing comb *size* is not always helpful--especially with different breeds, hens may have very different sized combs. Leghorn hens have very large combs that flop over, while Easter Eggers have compact pea combs, barely there by comparison.
A hen who is laying well will also have a moist, pink vent, and a wide, plump pelvis. The legs of a good layer may also be paler or "bleached" (in brown egg laying breeds with yellow legs). A poor layer will have lots of pigment. Hens who are good layers may also have broken feathers, simply because their bodies may put fewer resources into their plumage. Make sure your layers have a high protein diet with plenty of calcium for strong egg shells, and so they can maintain the health and gloss of their plumage at the same time.