My silkies are about 4 weeks old. Two I am now pretty sure are going to be Roos. Do silkies usually get streamers this young? The second picture "Dave" of his aren't so noticeable but the first picture "Taco" you can really see his steamers.
Body mass is going to be the best indicator during development for male vs female. The male silkies will for sure put on weight at a much faster rate. Silkies are so slow to develop distinguishing characteristics otherwise at least that has been my experience.