I start feeding my plants nutrients after the nutrients start wearing off in my loaded soil. I usually use happy frog soil (like your MG blend has nutrients already in it) and transplant them to a bigger pot three times before they land in their final pot. After they have been in their final Pot for about three weeks I mix up nutrients In their drinking water about every 10 days or so in between regular plain water feedings.
I use this line from Advanced nutrients but there are many choices on what to use here.
it is also important to add CalMag to keep your leaves looking nice as without it you will start to wonder what do my plants need and why do my leaves look like this? They are probably crying for Cal-Mag so it’s best to give them some so they don’t have to scream out for it.
I use this stuff but again others use other brands, I’m not sure it matters…