I usually start adding nutrients around day ten. Personally, I use Greenleaf nutrients megacrop one part….. promix is an inert media, basically just peat, perlite (I recommend to add extra perlite, which will make what you have basically into promix HP), mycos, and lime. Everything else you need to add. If you choose to use megacrop, there’s a promo code on their site for a free bag, just pay shipping. Good luck, and tag me if you have more questionsThe problem I have is the promix moisture potting soil bag has no npk value unfortunately (unlike the HF). Can't figure why they wouldnt just put the analysis on the bag or website