The basic way to tell if ur feed is to high is watch for burning on the leaf tips. Keep a eye on new growth for to much feed and genuinely if ur under feeding the leafs will yellow and wilt from the bottom up.
As for watering I go by weight of the pots. Once they fill light will give a good soak and leave to dry out again. fabric pots help u from over watering as they will dry out quickly. If u want a feed chart to follow, I'd recommend the one for ur feed brand, every brand has different ec/ppm levels and schedules.
And don't forget pH, nutrients can only been used by the plant in the right pH range.