Well its entirely up to you, I cant speak for foxfarms all I can speak for is my own personal views on how i would like to do things and I personally would prefer to know exactly whats going on in the soil. I see all kinds of soil growers getting through the first stage of the grow fine, because the soil is still heavily enriched, but once you get to that flowering stage, people are unsure of how much to put in whats already in, you see lots of soil growers getting lots of yellow leaves on the lower part of the plant. I'm not saying this is the way with everyone but you have to have a good amount of experience to know what and when to put in. If you had nothing in there to begin with, you could track the progress better and quicker because you could align it with the nutes you had put in.