DD9 was late choosing a hand... somewhere between 4 and 5 she decided to stick with the right hand. She has since been diagnosed with dyslexia, and this can be an early sign. Her brother is 3 and he has no idea which hand he is... he is just like your little guy, keeps trying both out. Their grandfather is ambidexterous and their uncle and great-grandfather were left-handed. I would not be surprised with DS ends up using his left hand.

Tomorrow is always fresh, with no mistakes in it. — L.M. Montgomery