Stuttering goes away in 80-90% of cases with developmental stuttering. It is natural for a child to stutter during the developmental phase. I'd let it be, especially if he doesn't like to talk about his speech. Best not to make him any more self-conscious at this stage. I'd start taking steps after he's 5 or 6 and has started preschool or school. If his speech is still a problem then, to the point of making it harder for him to socialize or interfering with his learning, then it requires intervention. How is he with other children?