How long until able to sex my ducklings?

[LeslieMiikal]

Im thinking more amd mor that other light coloured duck is a drake, its bill looks bigger and wider and the feathers though lighter then the other drake, are not the same as the little duck.

 

[LeslieMiikal]

Swede cross is a duck, started quacking today when I picked her up to look at her head and neck to see if there were any marks coming lol. So 2 girls, 1 boy, 1 probable boy.