One of my bug bears: (FLOSS) software which sticks at 0.x version numbers for a long time, sometimes years! Once you have something that many people are using for real use, it's time for a 1.0 release. What are you waiting for?
@HerraBRE semver says that 0.x.y can change for any reason, that you shouldn't rely on anything. I think that's a good rule of thumb. If you think people can rely on some part of it changing, then maybe it's time for a major number release