Our DD was also similar in many ways at that age. We had her start preschool at a small, Reggio-inspired, Spanish immersion preschool at 2.5. Probably not necessary for all kids, but we both work and keeping her in toddler-aged daycare was not going to work for her any longer. Her preschool teacher urged us to get her tested, which we did at 3.4. We collaborated with her preschool teacher, the psychologist who tested her, and the Head of School and teachers at her current school to determine the most appropriate placement for her for this past school year. She entered K in fall 2013 at 3.8 and thrived there. She'll start first grade this fall.
The psychologist we consulted recommended testing at young ages only if it will impact your academic plan for your child. If he's going to be home with you regardless, you can just follow his lead and enjoy the next few years learning with him! If you're looking for school/care placement, it might be worth looking into having him tested. Information is almost always a good thing.
