Age to determine sex if scorpions

[Spidermolt]

I tried looking this question up without any good answers so I figured that I'll just start a new post. So about what age/instar can I start to determine the sex of scorplings? I have heterometrus scorplings that I'm giving away soon but I would like to keep one baby and when it gets adult size I'll move it back in with its mother. They're only 3rd instar now and sexing them at the moment is basically impossible (for me at least) and I would like to pick a female so when I do move her in with its mother I won't have to worry about her getting pregnant.

 

[jm2628]

Old post with no answer, can we bump this to the top. I have three emps roughly 2" in size with a white telson. Trying to determine sex

 

[Mordax8393]

pectine counts work at any age