I wouldn't feed till the nutrients in the Miracle Grow burn-off. And with your MG, I'd give a 1/4 dose the first time, if necessary. The plants will let you know.
Cannabis eprefers a wet-dry cycle. So let the soil dry quite a bit between waterings. The more you water, the more nutrients are released, so don't keep watering to keep the soil wet. The moisture control formula will hold the moisture almost too much, so use care. Best to err on the side of underwatering a tad than overwatering a tad.
Might want to check some of the grow logs to see what other's are using for flowering, and why. But I'd go with something with at least half as much nitrogen than phosphorous, and at a lower N-P-K rate. (the lower the numbers, the 'lighter' the solution at the recommended dilution) I use Fox Farms Tiger Bloom and mollasses. I haven't foliar sprayed a plant in a few years. Still unsure why the need or desire... If you're using a solid nutrient, one shouldn't need to clog stomata and risk over/over feeding, lockouts, burn...
Most MG nutrient products I've used, the recommended dosages are for a 10 day to 2 week period. Keep that in mind...