Tail growth is not a sex indicator in silkies. Crests (poofs) develope at different rates on different chicks. Silkies roosters that grow up together generally get along great. There are really no early sex indicators in silkies except that some males develop an early comb. Any red in the comb is usually a sign of a roo.
Thank you, peepblessed. I appreciate your comments and experience. I've read that silkie roosters are generally nice little guys! Problem is I can't have them in my town. :(
The worst case scenario would be that I have all or mostly boys, because I would be worried replacing them with more silkies later and trying to introduce them to my little flock-- since it also has a few large birds too. I wouldn't want the new silkie chicks to get picked on by the older gals. Right now, everyone is in the brooder together! :)
I'll watch for red combs!