I agree with other posts, it really depends on the dogs, on your pack status, on how much you really want your birds to freerange. I have two high prey dogs, one of which was already livestock ready. I had to introduce birds to my lab/BC cross pup at the tender age of 7 months. He is a VERY high prey dog who is also hyperactive, to boot. He has snatched songbirds out of the air and swallowed them whole.....
Puked them right back out, but he still managed to catch them, which is pretty amazing to me!
When I first got this new flock, they were tied up and lying on the ground and I watched just how curious he was. He was very curious! It all starts there, you know. How you react to
their curiosity with YOUR chickens. If your dog is smart, if you are the definite leader of your pack, if you are right on with your corrections and you mimic how the dogs normally do it.....I would say you may have a chance. If my pup hadn't responded to the training, HE would be tied to a run or penned, and the chickens would be roaming free, not the other way around.