I like using 1/3 coco coir, 1/3 or a bit more perlite, and 1/3 or somewhat less wormcastings. I'm experimenting with a version of that soil, but with some budswel and foxfarm starter fertilizer added, as well as some trace minerals. I'd like to have a soil that needs very little fertilization, or none, and instead I just transplant into a bigger pot for bloom that's the same mix, instead of adding fertilizer. Many organic soil components are slow-release, so watering shouldn't result in a significant loss of nutrients, it may actually make them more available.