Well, I am not an expert but, silkies are not good egg producers because they go broody so much. The cochins and brahmas go broody too. So this cuts down on over all quantity. While laying you could expect maybe an egg every other day from each one. Brahmas generally will lay more eggs than cochins. I have 10 cochin banties that have just started laying and I am getting 4 eggs a day. I expect the quantity will go up as they mature a little more but when they go broody, they lay no eggs. I do not know about the ameraucana as far as broodiness or quantity. Hopefully someone else can inform you.
My cochins and one brahma started laying at 20 to 21 weeks.
Gayle
Chi lady in Michigan