I received my straight run of Polish chicks (4 White Crested Blue & 4 Bearded Golden Laced) back on June 6th and from experience, I can tell you that the head feathers are the main characteristic for telling them apart! Waiting for tail feathers and wing feathers can be daunting, and as with mine, looking at wing and tail feathers can truly throw you off unless they are 10 weeks or older, and maybe not even then!
Watching closely over the past couple of months, the head feathers were accurate at 100%! You will see that at between 6 and 8 weeks when the crest feathers are in bloom!
At 6 weeks my 2- White Crested Blue Polish roos were sprouting their Wattles! The females did not have any wattles so that was an easy tell! But both males had the spikey, needle looking feathers in their crest, sorta like looking at a punk hairdo from the back, and the females had smooth, rounded, and a soft head feathering, with a much softer look all around! Like little white mushrooms on their heads!
The golden Laced did the same but with the beards, it was a little harder to sex them...but the head feathers on the 2 males were spikey and irregular growing while the female's feathers were soft, flowing and had rounded ends!
My Polish chicks matured very quickly and all 4 roos are crowing already! They have been crowing for the past three weeks! All 8 have been integrated with the main flock of 21- beautiful (a mixed variety) hens and one White Crested Black Polish roo! He, Poli, is a fantastic, gracious, and friendly roo, and he is the reason we decided we wanted to add more of the Polish breed to our flock! And so far we have not been let down! Oh, and his crest came in the same way as the other roos' and he matured early! He was crowing at around 6 weeks!