First time using soilless

So got me growing in some soilless Nectar of the Gods. The seedling is about 4 days old. I was going to wait till the round leaves fall off and then start feeding her some nutrients. Figure start out at half strength. I am using Fox Farms trio. Been spraying with 5.8pH water and today was the first day it got first real watering. 1 cup of water with no runoff. I plan to follow the FFtrio feeding schedule. What do they consider a seedling? round leaves gone?

I use sunshine mix #4 which is a soiless medium and I don’t start feeding until the 4th or 5th node. I don’t use fox farm though so I probably didn’t answer your question.