I always start feeding , lightly, right off the bat. That soil should be fine as is (won't burn), but I like giving my plants a little bump. By the time I get to bloom stage I am going balls out, like 1000 PPM / 6.3 PH. It seems to work for me
if that works for you im happy..
not at all how I do it
fox farm soil has enough in it for 4 to 6 weeks provided your pot is large enough
I got plants in 6" pots that are 1ft tall and topped 1x that just asked for food a week ago and that's only cuz the pot is too small and there root bound
it light on calcium and magnesium so calmag is the only thing required... unless your organic then you might pre-amend with some gypsum to get the calcium
unless you've got a long veg time you really shouldn't need much if any fertilizer until bloom
and even then I keep the EC/ppm low and add basic tea and compost, a little Epsom salt and a calcium supplement