They are small for a month old but they look healthy. They'll eventually hit a point when they have enough leaves to grow rapidly. Just make sure you're feeding them enough or they will be lanky. I prefer to enrich the soil rather than feed liquids outdoors especially in the ground. Sometimes it can rain 2 or 3 times in a week and you won't be able to feed them so they loose out on feed
Never seen that brand of myco before. Imo looks like cheap junk mixed with cheap nutes.
Check out promix mycos, or dynomyco.
When buying mycos ALWAYS look for viable spore count. Most cheap myco products will state xxx 'propogules' all that means is there's a piece of a spore it doesnt have to be viable. Propogules vs viable spore count. And the ultra junk won't even show any kind of count as they don't want you to know there's not much of what your paying for in there.