My goal is to become a singer/guitarist in a band one day, so like James Hetfield, Matt Heafy and people like that. It’s a loooooong way to go though, haha. Besides guitar, I also practice screaming, because I can’t sing well yet. For singing it’s the best to have a vocal coach, and that’s what I’ll do, but for now I’ll focus on guitar learning first.
So my advice is to get a vocal coach once you’re able to play guitar decently. If you are already a decent guitar player, try to find a vocal coach asap.