Rigid Norms or Communal Comfort

We were at the very beginning of the discussion. I had gone over the norms. One of our central norms is “one mic” or that one student speaks at a time while everyone else listens. I called on the first student. As they started to speak, a couple students immediately started having a side conversation. I thought to myself, "Oh no! How do I get them to follow the norms we just reviewed and agreed on?" I felt I needed to address the side conversation and reassert our one mic norm to make sure everything didn't go out the window right at the beginning. I also knew that it was important for me, a new, young, female teacher, to be an authority figure in the classroom. But, philosophically I believed that relationship-building and student comfort are necessary for students to learn. I had come to realize that building strong relationships is far more effective than asserting authority when it comes to getting students to follow norms. In that moment, I was more concerned that if they became annoyed with me, reasserting the norm might pull focus away from the discussion and discourage their participation. It could have created a distraction rather than supporting the discussion environment. How could I set the tone of the discussion as serious but also relaxed enough that students would feel comfortable contributing and thinking out loud as they work through the difficult questions we were tackling?