As far as I’m aware, the music repository hasn’t been active in years, and no one uploads anything here anymore. People usually just upload music on the main repository thread or make their own threads and post their music there.
It is up to you as to when you want to upload the ost. I would do whatever you think would grab the most attention to your work I suppose.
Since the specific music repository is no longer active, you can name the files however you want. I just name my .s files using the traditional format though:
Game Title - “Song Title” {Username}
If the game is from a FE game, then I just use FE1, FE2, FE3, etc. But again, there no longer is any actual format.