Double grape auto

Got 6/7 sprouts and transplanted them to 3 gallon pots of bar harbor blend by coast of Maine. The bottom of the pot has a thin layer of compost and the top has a thin layer of fox farm happy frog seed starter soils keeping the soil moist at all times. I looked the bar harbor blend and it says not to add nutrients for. Minimum of 3 weeks. So that’s exactly what I will do. But come the 3 week mark I will only add oyster shells and epsom salt for cal mag and sulfur. This will be the only top dressing I give it. Than it will be weak solutions of worm tea, kelp tea, liquid fish emulsion and sugar feedings.