How long beore I should sex seedlings>?

How long before I should sex seedlings>?
and is there any disadvantage other then delayed growth
by sexing the actual seedlings as opposed to a cutting?

some people 12/12 as soon as they pop out the dirt. I personally would wait at least until they have their 2nd set of "true leaves" until sexing.

the only disadvantage to sexing anything before there are preflowers is that it will take a bit longer to determine sex. but they continue to "veg" until that point, so there really no hurt.

great thanks.. is there any advantage to keeping the mom out of flower completely? and sexing a cutting rather then the whole plant??
I intend on keeping her around a while

if you are unsure on the sex yes. taking a clone rooting then flowering it should give you the sex of the mother. and then you can take multiple clones from the mother, then flower it.

taking clones from a mother in flower adds to the veg time a bit.

Right on.. So putting the plants which are from seed into 12/12 and then back to 18/6 once sex is determined won't have any adverse effects..
.. other then a small delay in growth while it recoups from the trauma.
I've had them under 18/6 for about 2 weeks and want to weed out males before any space gets wasted, just don't want to limit the life and
potential of the females that I keep.. It's worth the extra time for me to ensure the long term sustainability of the moms.

I wouldn't 12/12 anything I intended to keep as a host plant. It's just stressful and not needed.

Plants will show sex on their own, 5-8 weeks from seed, regardless of the light cycle.

You could also take a cutting, put it in a glass of water (doesn't need to be rooted), put it under 12/12 and it will survive long enough to show sex. Simple and no stress to the host plant.

Wet