When to know if they are mature enough?

[mkelle11]

So, we got some hatching eggs this april, and ended up (Of course) with 16 Roos and 4 hens. We do not want that many roosters around, and definately don't want to hold them through the winter, so we decided to butcher them. We've never butchered anything before, and are wondering when we know if they are mature enough?

They are Comets, (With the exception of some Light Brahmas, but we might not kill those yet because we honestly can't tell which are hens yet) and have been allowed to be free-range, with access to meat-bird feed (Although, I admit, sometimes it's replaced with Layer or Gamebird, as we are not always the best at getting to the store and have hens and peafowl) . We wouldn't be butchering for a few weeks yet, as we are waiting for it to get chillier so there are not any bugs... But I'm wondering if they look old enough?

These are them.....They are the whitish ones, the brown ones are the hens, and the greys are the LBs.

 

[Amyable]

My thinking is it would depend on what size carcass you want. This is per "The Joy of Keeping Chickens" by Jennifer Megyesi:
broilers - 3-4.5lb, less than 4 months old (hybrids and heritage)
roasters - 5-9lb (mostly hybrids, heritage have tougher texture)