Deb, the lone Australorp might take 5 months to start laying but it is a good layer, the Silkies, while not the best layers, are loved by many. The Australorp that is left might need a friend, not to enable the whole chicken math thing, just because chickens are social animals and love companionship. Even if it is only one other of their kind. Then again, she may get along just fine with the silkies. Enjoy your new flock and welcome home to BYC.
Hi! Welcome to BYC! Sorry for your early losses. I agree the Australorp needs a friend in her size category if not her same breed. My Australorps hang out with each other and not so much with the other breeds I have. Chickens are very social creatures.