At this point I'd just wait until the transplant. You'll do more harm than good if you try to mix perlite in there now, it'll damage the root system and potentially kill the seedling at that age. Dark green foliage and leaf curl are both signs of too much nitrogen. Luckily, nitrogen is extremely water soluble, so try giving it a decent drink of straight water (enough to provide quite a bit of runoff) and flush some of the excess nitrogen out of there.
We all learn from our mistakes. I could probably just about write a book just on what not to do.. But that's what separates the good growers from the bad ones, you have to know what you did wrong, why you did it, why it was wrong, and never make the same mistake again. Don't be too hard on yourself, organics (when not done properly) can be really difficult. With organics you have the least amount of control out of all the methods of growing. It all starts with a good foundation of sweet sweet earth, but if you accidently dumped too much blood meal in there (or too much of anything) you'll be chasing your tail trying to keep it in check. The best advise I've had in organics is to grow good soil and the plant will follow. And use compost teas, your dirt will love you for it (and your plant will love your dirt for it).
In my grow room right now I have a usda organic white rhino next to a dwc white rhino and a white lavender in coco, I call the organic rhino goliath.....