. I have read that starting them on layer food too soon can have them laying earlier, but it is not good for them because of an excess of calcium. I have friends who feed all their birds layer food and just grind it for the babies. There chickens seem to lay earlier than mine.
I do what is recommended on my feed as to when to start layer feed and the oyster shell. Feed could account for some of the differences. I am assuming your feeding a layer feed at 8 months, but if not I would have them on oyster shell and making sure they have the layer nutrients.
Layer feed can't cause birds to lay earlier. It's not as if it contains some special laying supplement that makes them lay - it's the same as any other feed except that it has the exact minimum protein and calcium content required by adult chickens. Given the choice, birds will only eat calcium when their bodies require it - a 16 week old will eat oyster shell if she knows she's going to lay at 17 weeks, and a 25 week old will eat oyster shell if she knows she's going to lay at 26 weeks.
I feel the need to mention this - and make no mistake, I don't go around telling people how to care for their animals, as everybody has their own method - but it really concerns me when I hear of animals who are possibly in danger due to woefully ignorant (or even stubborn?) owners. I can tell you, layer feed has a
serious detrimental impact on birds younger than 16 weeks; specifically, it does a lot of harm to the kidneys. The younger they are, the worse the effect usually is - a 14 week old isn't gonna have a huge of damage done from layer feed, but an 8 week old? A 4 week old? A 1 week old? It's not likely to kill them immediately but it's liable to do severe long term damage to their internal organs, and I'd be very surprised if it didn't shorten their lifespans by quite a bit. This isn't even mentioning the very low protein content, which can easily result in scrawny, stunted birds. Again, please understand that I know everybody including your friend(s) have their own method of keep, but this is not a good way of ensuring bird's long term health and survival.
Just to say, the correct age to switch to layer is 16 weeks. This is about 1 month before most hens will start to lay, but right at the correct age that the earliest few will. This provides immediate support to early layers and allows later hens to begin building up calcium in order to form strong, healthy first eggs.
(For those who want a source, I work at a poultry specialty store and we are required to know this stuff in order to answer questions people may have about the correct type of feed to buy. I was taught this information by my boss who has 35+ years experience and who has discussed this extensively with the feed company we purchase from.)
I'm hoping my cock bird is not a dud. lol I don't think I have ever even heard him crow! I'm used to slow growers, as i have Brahmas as well, but it seems like they're taking forever. Thanks again y'all!! 
