P.M.
Stay away from the academics unless he's genuinely interested. He's going to get that learning, in small, appropriate steps, in preschool. Right now, he needs play, play, and more play, to build his imagination, his vocabulary, help him understand his place in family and the larger society, and help him develop motor skills and exercise his cute little body.
The size of a child's vocabulary is the single most reliable predictor of their future success in school. Reading to him is wonderful. Counting and the ABC song, or manipulating alphabet magnets, can be fine during all this play, but don't sit him down like a little student and give him work to do yet. Very few children show early gains from that approach, and even if they do, it all levels out by around 4th grade.