As it was my side project and I had little time to invest in it, I needed to be efficient.
After 3-4 episodes I've noticed that the best way to grow the subscribers was consistently posting new episodes. So that's what I focused on.
I also shared info about the new episodes on Twitter and 10 different Discord channels. Now I'm working to find a way to promote it more on Twitter. I'm experimenting with short Headliner videos that let me share soundbites with Twitter audience.