I've never heard anyone giving names to their plants this is so cute, I think I might start doing that, imagine rolling one up and saying "I'm smoking Jade right now, she was such a healthy girl"
Your seedling is likely still relying on the nutrients stored in the seed, so hold off on feeding for now. A lighter green color might indicate insufficient light rather than nutrient deficiency. Prioritize providing ample light, consistent watering, and good airflow.