Seedling leaf color is very light green.

Quite normal and no real need for concern, it is just getting its root system organized before worrying about growing perfect leaves. It is only a slight variation in chlorophyll maturity and by the second or third set of leaves, you will be wondering why you were worried in the first place! Yes, don't leave transplanting too long, those pots are not large enough for much more than 1-2 weeks of growth. Ideally, pots about 4 inches across and 5 inches deep are far more suitable, as their volume allows for good root development and growth for about 3 weeks. Congratulations for experimenting with "Mykos", I believe they are the secret ingredient every grower should be aware of, their benefit is remarkable and their value to plant health can not be underestimated. I am a complete fan of it myself and can not ever imagine growing without it! Hope this helps, Organoman.