Welcome to 420
@rjgrowbig
I run sterile hydro and I put the seeds in rock wool and the reservoir immediately after germination. I don't have issues. Make sure you get the nutrient solution correct for the growth stage you are in. If you run LEDs you will need to add CalMag.
If you are using regular seeds, check out this site
LeafWorks® Cannabis & Hemp DNA Sex Test. It will be worth the fifteen dollars and you can test the sex after a couple of leaf nodes, long before pollen can be an issue. It can also save a lot of $$$$ worth of nutrients.
I would leave the plants at 18/6 until they achieve 1/2 of your desired size.