Growth stopped

In nature a lot of Seeds die. No water = no root. End. It is just easier in a small one to water it correctly. A big one is ok, too. Just not so easy.

Coco has no nutrients.........are you feeding them? Almost impossible to over water in coco...........water the entire pot until run off........not just in small circles or just next to the plant........roots will not grow into dry areas. Size of pot is fine, no need to start in "mini pots"...........what do people think happens in nature when plants grow in the ground??

There fine those just rooting in now, don't water too much

Maybe only water lightly around the base of the plant(after letting her dry). How far are you from light source? At that stage I keep them pretty close.

the pot is to big. better to start with a mini pot - otherwise it is not so easy to be on point with the watering. The plant is now exploring the root zone - which is large. after getting to the bottom it will start again to grow. (but why there is dirt on your newborn? it could infect the newborn with some fungus or other bad stuff)