You can put germinated seeds directly into neoprene collars. It is a bit tricky however, and there is significant room for error--- I suggest buying a 99 cent bag of lentils from the grocery store and germinating them and trying it first with them, so you can get the hang of it.
A more common approach is to fill a 2 inch net cup with hydroton. Much simpler, but still has quite a bit of room for error. See if your hydro shop has the very small hydroton. In the small basket with the regular sized hydroton, the seed has a tendency to migrate downwards near the bottom edge of the cup. The smaller hydroton helps mitigate this problem.
If you are nervous about accidentally wasting your seeds in your NFT, then try to grow something else first. I would suggest a crop that is productive early on like lettuce or herbs. Sure, they grow differently than weed, but you will gain valuable experience, and you will be confident about the abilities of your system before you drop that expensive seed in.
Both feminized seeds and autos have a higher probability of turning hermie. The plant's genetics are set in stone once the seed is created, but stress on the plant can force it to produce male pollen sacs. (normal females will sometimes create pollen sacs at the very end of their life cycle. Likely an evolutionary response to propagate the species if no males are available). Causing too much stress to ANY weed plant can cause the plant to grow pollen sacs, but it's most common among feminized and autos. Too much of anything can do it-- stress from improper lighting, temperature, humidity, root zone temperature, pH, PPM, too much pruning, etc. Anything that makes the plant have to do a lot of work to recover has the potential to (but won't always) force the female to grow pollen sacs. (Its like cancer in humans. We know a million things that have the potential to cause cancer. Avoiding them will reduce your likelihood. But not all people who are exposed to these things will get cancer, and some people who are exposed to little or no carcinogens in their lifetime will still get cancer). So you do your best to make sure your plants are not unusually stresses, and cross your fingers.
