Naga's and scorpions seem more difficult to start and grow than others, my scorpions are going very slowly, in fact I can't identify if they are stull growing or not....
I have 5 brain strain seedlings going mad, I treat them a little worse than they should, cause they are still somewhat young you can see the leaves getting affected by all the heat, they're usually noraml by sunset though.
Just take care of them like any other pepper plant, and they will thrive. Be careful when eating them though, cause until you do, you will never be ready for them, I know from experience, they're a wonderful pepper, and far hotter than anything I've ever tried, including the scorpions.