100% coco? Im running 70/30 coco and mine were in between the size of your largest and smallest plant on day 12. On average mine were around the size of your plant in the second last photo. I’m fairly certain I stunted mine for a period due to overwatering and watering seedlings until runoff. I was on the fence about starting over, but things are looking better. I’ll be putting up photos later this week so you can compare. They’re beginning to bounce back now and grew 3-4x their size in less than a week after I allowed soil to dry more between watering and they appear to be at the point where they can tolerate watering until runoff.