I think your plants are WAY to young and small to be showing ANY signs of a deficiency, two sets of leaves doesn't say too much about a plant's health unless they are very noticeable. The leaf curling is the equivalent of a pimple...it is too small to be life threatening and it will probably heal on it's own very quickly. Don't woory too much about your first set of leaves or two... they often get damaged or gimpy. You need to pay attention mostly to the new growth and make sure it looks healthy, since plants don't heal earlier injuries... they just allow the damaged areas to die off and grow new leaves instead of healing damaged ones. The amount of nutrients used by young plants is miniscule... even a plant a few ft tall uses very little. If you compare the fertilizer use of a regular corn farmer and compare it to what many growers dump on their plants, the farmer could probably plant 2-3 more fields of crops using the same amount per plant. Many newer growers think that the more that you feed them, the more massive they will become, but it doesn't work like that for the most part. In my last 4 grows, each one roughly 6-7, 7 ft plants in 6 gallon buckets, I've used half a container of nutrients (Jacks 20-20-20 or a Blooming mix with less nitrogen and more of the others.) which isn't too much compared to what some feel is necessary
OK...I'm done preaching. Plants usually sprout with enough energy to get them started, and when starting, their feeding requirements are tiny. A plant 7-8' tall uses a lot more nutrients than a 2 ft tall SCROG, but even the big plants don't take too much, IMHO.