The cockerel / rooster saddle and hackle feathers will be pointed. Pullets / hens will have rounded saddle and hackle feathers. Pullet / hen saddle and hackle feathers will also be less pronounced than in males. I circled the saddle feathers on one of my Orp roosters for reference. You should be able to see them by 3.5 months old or sooner. Looks like yours have lost all of their chick down.
The darker patch on the saddle area are the male specific feathers coming in. It's hard to see, but if you zoom in and look close, they are pointed and shiny.