Go to the american livestock breeds conservatory website, then to their downloads page. There is free information on how to choose for egg & meat production with flock improvement. They used Buckeyes as a base for the study, but the same information could be used for other breeds. Here's the link to the main page http://www.albc-usa.org/
Until you are confident and sure about culling choices I would let the birds mature more. Orpingtons are slow to mature anyways.
Some people are good enough to start culling as the chicks come out of the incubator, but I'm not that confident yet.
Mine get to stick around for a month or so before I start seeing flaws I don't need hanging around. Those will get sold or eaten.
Until you are confident and sure about culling choices I would let the birds mature more. Orpingtons are slow to mature anyways.
Some people are good enough to start culling as the chicks come out of the incubator, but I'm not that confident yet.
