How old do they have to be before they can be sexed, and how?

[sophiejw]

I've got a couple of day old Buff Orpington chicks- they are soo cute

How old do they have to be before I can start to have an idea of what sex they might be, and what should I look out for?

I have some 2 week old "DejaBlues" which are a blue egg hybrid. And 4 day old other blue egg laying hybrid (mum is cotswold legbar or a ee, dad is either a white star or a ee). Any idea of how to sex hybrids? I guess they are ee's.

Also, I'm just about to start the next incubator run- Black and Blue Copper Marans, Silver Spangled Hamburghs, Columbian Blacktails (rir x light sussex). Any tips of when / how to sex these too would be very helpful.

Any advice would be much appreciated