This is the first one. It's pretty obvious he's a cockerel. This is weasel and he's 14 weeks old. He's crowing already and is very sweet. He's seeming to keep his hen feathering, which I am hoping for. His sickle/hackle feathers are rounded and usually both hens and roosters of the Sebright breed will have this. He has a very large single comb already.
This is a 13 week old porcelain d'uccle. Her name is lady and she is a female.

her comb is still pretty tiny and is just starting to pink at this age. Usually d'uccle cockerels will already have a lot of pink and a larger comb at this age.
This is Giovanni, he's from a flock last year. He's about 13-14 weeks in this picture and you can see he is developing his comb nicely. He started developing it noticeably at 6 weeks and I could tell for sure at 8 weeks. He also grew a large single comb and was very beautiful.
Giovanni after he grew in all his plumage
Next is my Sebright pullet, pancake. She is the same age as the first Sebright (14 weeks) but you can see she has a lot of black in her comb. She has a rose comb.
This is Mikey, and he is 14 weeks as well. He has a rose comb and was in the same batch as pancake above. ^ he has had pink in his rose comb since he was about 7 weeks old. He isn't showing signs of hen feathering like sebrights usually do.
14 week old Elvis, showing some nice hen feathering so far. He has been the slowest maturing and didn't get pink in his comb until about a week after the other cockerels.
Finally, Garfield at 14 weeks of age. He has a single comb and I noticed pink in it first at 8 weeks.
I mostly have cockerels, luck of the draw and 3 of my Sebright pullets didn't make it. But hopefully this can give you some info on what to look for at certain ages.
