Why do people listen to you, and how long does it take?
Whether or not people perceive you as a “credible source” depends on a lot of factors. One of those factors is whether or not you actually know what you’re talking about, but sadly that’s not the only factor. Some people just take time to trust other sources, other people want external validation on your opinions, and sometimes people need “social permission” to take you seriously.
People are bad, generally, at evaluating information they don’t already possess. If I don’t know anything about nuclear physics, then how can I tell if someone else does just by listening to them?
So people jump through all sorts of hoops to convince other people that they’re credible, and people jump through all sorts of hoops to confirm whether someone else isn’t a charlatan.
Wouldn’t it be great to skip all that? To not have to go through the motions of proving yourself correct, getting external validation, etc. before people would trust you?
You totally can!
Don’t wait until someone has an existing interaction with you to begin forging your credibility. Pick your topic of expertise, and just start talking about it. A lot. Loudly. Publicly. Every chance you get.
Write papers on it. Articles and blog posts. Make videos. Put it all out there.
When you attract people into your circle this way, you’re naturally attracting people to you based on the fact that they find you credible. So by the time you have your first actual conversation with them, they already think you know what you’re talking about. They’ll have already verified to the level they need.
Don’t try to live up to your credentials. Make sure they’re living up to you.