Keeping track of chickens

Novice questions. I intend to build a laying flock as cheaply as possible, which may include (a) purchasing smaller groups of chicks annually and (b) picking up already-laying chickens who are unwanted or excess, from some neighbors. Let's assume that my flock gets too big for me to keep track of individual chickens. How do I know when a specific chicken is past its egg-laying prime? If a hen only has 2-3 years of prime laying, presumably I would cull that chicken from my flock (e.g. chicken soup) at the point where it is no longer laying enough to justify the feed cost.

Do you identify different generations of chickens, or just different individual chickens, by somehow tagging them? What's a cheap and effective tag to use? Can you leg tag them using different colors of cable ties?

Related questions:

How do you know the laying frequency of a specific chicken? I see posts on here that someone has got a specific chicken which laid XXX number of eggs in a year. In a big flock is there any way to know which chicken is laying which eggs, or do you just track egg production on a flockwide baasis once your flock exceeds several chickens?

Is there any way to tell whether a chicken which someone else is giving you is past its prime laying years?

Thanks

GG

I am trying to figure out the same thing. I purchased some leg bandettes all in blue. I figure that those are for this years birds. Next season I will buy a different color so I can keep track of each bird by season. Each bandette has a number on it which can be recorded. I also thought about giving each bird a name based on alphabet. First group of birds all start with "A". Next set of birds all have names beginning with "B". If you have a lot of birds that can get complicated really fast, so that idea may be dropped. I just hope that the bandettes stay on.

You can keep a bird log with eggs and all kind of info when you start with chickens.
I will write in the date I get them age breed and eggs I get from them. At one point I had almost 200 birds but I sell some and eat some and write this down too to keep records. The ones that die I write up too.
I always make sure when I buy birds that I have at least 10 birds in a flock from the same age, different breeds, so I have eggs year round and when i have to replace them the whole bunch has to go.
It's easier to get them apart them because of the age differences.
Some people use bands that kids use for their pony tales with different colors. Make sure that when you do this to replace them while the chick is growing, other wise it will grow into the skin.
Good luck

I don't let my chickens to get older then a year old because if I want to eat them the meat is still nice and if I want to sell it ,they are still good for a while for eggs.
I sell my chickens to buy feed or new chickens.