Are they all the same breed? How old are they?
Unless one uses a strict lighting program, it's anybody's guess when they will start laying. Some start as early as 17 weeks, some at 26-30 weeks.
Keep in mind that, though they lay well the first year, they will molt the second autumn and every autumn thereafter. They take a laying break through molt and until they recover. Each year, they take a longer break.
Will you butcher them each time they start to molt and start over with new birds? That is what commercial egg farms do.
I have a friend that had her chickens that she loved for 3 years or so. They took a good winter break and she decided to give them away. It was early March. I called her and encouraged her to keep them a little longer but she had already made up her mind. As soon as she gave them away they all started laying in the next week. She fed them all winter and gave them away right before she was going to reap the rewards. As days get longer, even old hens will kick in and the eggs get bigger each year.