wow its so hard to tell . I just went through this same thing. Mine started crowing at about 12 weeks. But all are different. I had to send him back to the breeder and I was very sad. But I did learn a few things by having him. I noticed the male silkies hair is much more swept back looking. I also noticed his comb, although not big it was bigger than my others. also he was developing Hard Tail feathers inside the tail.Just a few but they were there. You know what you CAN do? Look online and find a lab that will DNA test him for sex. I did this with my two chicks. It is ONLY around 12.00 to do the test. Then some labs will give you results in two days after recieving the test. You can use feathers. Its fairly easy then you will know FOR SURE!!!