Need help sexing 4 week old chicks

[rinlareine]

The white chick is a mix with a rose comb. Should be almost four weeks old. I've heard that wyandottes mature early which is why I'm still hoping this is a hen.
The black and white chick is a mottled Cochin bantam and it may be five or six weeks old, not sure. If you think you know, please post! Thanks!

 

[Chicken Girl1]

The first one I'm leaning towards cockerel but am unsure on the other one.

 

[junebuggena]

The Wyandotte mix is a cockerel. The Cochin looks like a pullet for now, but that could change in a week or so.

 

[rinlareine]

Hmm, that's what I was afraid of. The pictures make the mix's comb look more red than it actually is, but it still seems too developed to be a pullet. The cochin's comb is actually more red around the base than the wyandotte mix. I also had a Lt. Brahma hen develop quickly like this as well, so I think I'm going to hold on to the white one for a bit longer. It feathered in quickly, unlike the cochin. Thanks for the input!