You'll have to make that decision yourself, obviously. With our different set-ups and goals, no one answer will be right for everyone. I think you are doing the right thing gathering information to make that decision.
On average, a hen will lay about 15% fewer eggs after each adult molt. Each hen is different and none can read, so they don't all know they are supposed to lay 15% less. I'm certainly not going to tell mine. But if you have a large enough number so you get statistically relevent results and they follow the norms, you will get about a 15% decrease on average. Some more, some less. It depends on your climate, when they were hatched and many other things, but the first adult molt is often when they are about 1-1/2 years old.
I'll tell you what I do. If I were free ranging them where they forage for most of their food, I'd probably do it differently.
In year one I have group A of pullets. They start laying in midsummer and often lay throughout the winter.
In year 2, I get group B of pullets, and keep Group A. Group A molts in the fall/winter and really cut back laying but group B usually keeps laying.
In the spring of year 3, I get group C of pullets. I keep group A throughout the laying season but retire them when they molt that fall/winter. By then group C is laying and Group b is going through a molt.
It takes three years to get this sytem set up and running. Good luck in figuring out what is right for you!
For BettyR, you can get colored plastic rings to go on their legs so you can tell them apart. I prefer the spiral. Many chicken supply places have them.
