Lavender Orpingtons - is there an easier way to tell gender?

[Nikkimik161]

Generally it takes 3-4 months at least before you start to see them. 4-5 before they start looking good. It's also harder to see on lavenders because they're self and tend to be a bit frazzled looking in the rump as it is

That helps a lot actually. I think the oldest are probably 10-12 weeks old. They are all different ages.