Well, generally it is better to wait until they are around 6 months old, but I'm sure there are quite experienced breeders that can do it earlier. I am out of practice a year or two, but I feel that is a female.
The first one definitely looks female. I'm not nearly as confident about the other two, but I'd say the 3rd one is male from how prominant the pores are and I see 2 bumps at the base of the tail. The 2nd one is I say female. Don't quote me though! Did you hatch them yourself or buy them from a store?
Thanks for the reply. Yes, I hatched them myself, they were incubated for mixed. So thats why I'm asking what other people think. It's only my second season breeding so I still need help.