Hen or Roo?

[indianaducks]

About 7 weeks old. (The brown one in front)
Also curious about the gray/white/black one behind. Same age.

I know the white leghorn in the back is a roo.

 

[ve]

Roos both. White one is boy also

 

[Rhodebar Lover]

Yikes, all cockerels!

 

[T Banks]

All cockerals

 

[indianaducks]

So I started with ducks and am newer to chickens. At what age do excess roosters become a problem? AKA at what point do I need to deal with my extra cockerels so there are no issues? Can I keep them for a few months until I see who is nice, or do I need to get rid of them soon? They are slightly varied in age but basically 6-10 weeks old.