He didn’t talk much for the first two years. In contrast each of our other 3 kids were amazingly fluent at 18 months. We were very concerned but our pediatrician was not. He said to just let it play out.
By age 3 he was talking a lot more but people had a hard time understanding him. So we explored speech therapy and the therapist said he was borderline. We, or course, could understand his unique way of saying certain words.
Now at age 5, and after two years of preschool, he shows improvements but some people still have a hard time understanding what he is saying.
We have decided 2 years of kindergarten will serve him better than one more year of pre k. He will grow out of it at some point and he is on track in every other metric. People just have a hard time understanding him.