First of all, and I cannot stress this enough apparently: these plants are not babies. They don't need to suck on your breasts to survive. They don't whine and piss in your face, nor do they crap in diapers that depend on you to be changed. They do not need to be cradled. Bed time stories and lullabies are optional, but the fact is that they do not need you. They might even grow better in some remote wilderness, without you.
If I was a cannabis plant, I would certainly be offended to hear so many damned people referring to me as a "baby".
I am pretty certain that you are over-feeding, due to the wavy leaves, curling under and presenting burned tips. It doesn't look very severe yet. I know you said you haven't fed it much, but the thing is that dry nutrients including Espoma Bio-Tone Starter Plus often contain slow acting fertilizer that is available over the long term. If you put too much, even anything over a quarter-cup per plant you might not see any negative signs for a little while. These nutrients also don't flush out very well. Scoop out the top layer of soil and replace if this is what you did, and it does kind of look like a dry-nutrient mix on top of the soil there...doesn't look like just perlite and soil to me, anyways.
Also, the Bio-Tone Starter Plus really isn't the ideal fertilizer for regular feeding anyways. It is a great organic fertilizer, with mycorrhizal fungi and assorted strains of beneficial bacteria. But as the name implies it is really for the purpose of amending soil to give the plants a good start. For instance, seedlings I suppose, and transplants. You mix 2.25 cups per cubic foot of soil, or alternately when transplanting simply sprinkle a bit of the stuff down near the root ball. The plants form a symbiotic relationship with the microbes and they'll grow more vigorously with enhanced resistance to disease.