There is no right or wrong approach to game dev. If that's what works for you, then that's what you should do. I heard some people make their game backwards lol. Ignoring music until after everything's done is a good approach though imo, you don't paint a door before it's made

It depends on what you mean by the main points of the story, but I think it is generally a good principle to create the frames/overall structure of your game before getting too far into the nitty gritty. Yanfly's comic series discusses this pretty early on here: http://yanfly.moe/2017/01/07/comic-lets-make-a-game/