It looks like you have at least 4, maybe 5 or 6 that are starting to get their male plumage coming in. Easiest way to tell for sure is by the sound of their voice. Otherwise within a week, you will know for sure if they get a colored head or not.
my Wuza has an ugly stance in this picture, but it's still good for an example. Notice his curled black tail feather, white lacing around the black tail feather, yellow/green bill color, dark iridescent green head, and mahogany color coming from his chest and spreading over his back. These are all good indicators of a welsh harlequin drake.
I see around 5 drakes here just based off coloring.
The drakes will have a low raspy frog like sound, and the females will start quacking early on.
And the drakes will also have a curly tail feather.