So I started out with about 10-15 Nagami Kumquat seedings, but a bunch died even though I gave heavy citrus fertilizer and I found out the key to getting them to grow better from seedlings and thought I would share.
So over watering is easy with citrus, which I found out the first round. You're supposed to water once a week.
Underwatering is equally easy.
What I found out is if you wrap the seedling in a clear plastic bag and up the humidity level, but keep the soil wet only once a week it will get past the first leaves faster than without the greenhouse effect. My most successful ones I basically put into a ziplock. High humidity+drier soil works spectacularly well. I have one now on third leaf set. (I only have 5 left...)