Who is Acharya?

 Who is following rules and regulations and at the same time he is preaching. Shyam Bhagwan also realised his mistake before Sri Chaitanya Mahaprabhu until dwapar yug, he just finished his duty to give advise.he did not show what to do and how to do. That's why he appeared in this yug.yes although he is s Bhagwan but he appeared as a devotee he hide himself ,he is bhagwan he hide and came in the svarop of devotee. He is Krishna his original body efflugence is shining black but he covered himself with golden color. So Swayam Bhagwan realised if i not show them by my activities general people will not follow so that's why sloka

First I do in front of everyone then the people will follow. So he start to do his own bhajan. krishna  himself is chanting the name of Krishna. When Krishna appeared here as sri gaur sundar as a devotee ,krishna himself he started to chant his own name krishna to teach us how to chant how to create our mood how to lament. In which way we have to developed our bhakti. so first he perform everything in front of us.