it takes at least 7-10 days before the plant changes cycles from veg to flower to sex. Then it starts to flower so give it at least 2 weeks but more like up to 3 weeks to get a good sex on them.

If you are going to put them back in veg once you sex them.....then you need to veg them for 2 weeks longer then if you would have cloned them for sex. It will take them about 10 day's to go from flower back to veg and there are some parts of the plant that will not go back to veg so know that too.

Cloning for sex is the safest method and less stress on the plant too.