It's rare but not unheard of. I know someone who started stuttering at like 18 or 22. You could ask your parents if you ever stuttered as a child, but tbh I don't know what that would tell you. I'd go see a board certified fluency specialist speech therapist, preferably one who's worked with a similar case if you can find them. My main advice would be to guard against developing bad habits. Don't switch words, dibt try to hide it, don't push or try to force words out. Know that stuttering isn't bad or wrong. And while it can be uncomfortable, it's you're not any lesser because of it so if you need to give yourself a little more time and patience, you do that. One thing you'll eventually learn is we care much more about our stuttering than anyone else.