You need a complete feed -- primary, secondary and trace.. treat it like hydro. calculate your ppms from labels. Keep pH 6.0-6.5 in coco, unless your fertilizer says specifically otherwise.
You feed every time in coco with ~20% runoff to prevent buildup. It is impossible to overwater, but an overly wet substrate all the time will have other negative impacts of course. A seedling early on is probably fine with buffered coco and just some hydration for 10-14 days. As long as you get good runoff, it doesn't matter though. Later on, multiple smaller feeds per day is better, if you can automate it and/or just around to do it, but not neccessary. cover top of substrate from light or you get algea.
Lucky for you, i highly doubt you have to be concerned about that coco brand. It should be ready to go, i bet.
i'd mix a fair amount of perlite.. more means less time between watering, of course. 10-20% at least for upto 5-gallong, then i'd start adding more (as a minimum). I like a higher percentage of perlite for roots later on when it gets compacted from time and watering.
Look into a better hydro feed, imo. you can't depend on the substrate to fill in the gaps at all. if their guaranteed analysis all adds up and sufficient, then i am wrong.