When you first get them, make sure you get some pellets from the breeder so that you can keep them on the same feed before transitioning over to a new brand of pellets if you want to. Some recommend unlimited pellets for rabbits up until around 6 months old, you probably don't need to give unlimited though, about a cup each would probably be plenty, but certainly speak to your breeder and your vet and ask their advice too. Initially you should continue with what your breeder was feeding before reducing the pellet amount down to about 1/4-1/2 cup of pellets per day per 5 pounds of rabbit for an adult rabbit.
Hope that helps.