I'm not exactly sure what the youngest one was, as some were quite small & I just used them for chicken stock.
There wasn't much meat on them, but it was better than totally wasting them.
The rest of the small ones I sent to an auction in Sept for someone else to finish growing out or whatever.
As far as ages, I went more by size than age. Though I saved their wing-band numbers, so I can eventually check.
I'd estimate though, some of the small/medium size ones were 8-10 weeks, perhaps 12 weeks.
Most of the ones I have left to process were hatched in March, April & May, perhaps a few stragglers left from June & July.
I'm not too particular, as I've been known to process old hens that others didn't think were "worth it", but I didn't want them to just get "thrown away".
Could have quoted a few comments, just did this one on processing to address all the rest. Not speaking to you in particular myfivegirls. I've asked the same thing, how young can you process, seems a waste to feed feed feed for ones you know will not be kept, when you have to many chickens and can clearly see early on what ones you know do not fit into your breeding program or are to many cockerels. The amount of feed $ you put into them does not get you much more meat for your $. That's a earlier age then I have done, but a good age, 8-12 weeks, I need to start doing that, said I would but I have a hard time with it.
Old hens, and roosters, I have a four quart pressure cooker, slow cooker crock pot takes longer but I think is better, I've over done some in the pressure cooker, you can monitor a little better the crock pot. They become tender for pot pies or soup either way.
I saw a super mean RIR rip his spur off in my fathers shoe, it was just the casing around it, guess they shed them like a snake skin, Lol!