This turned out a (short) size 2T.. But he’ll grow into it eventually!

CO 100 st on a small circular needle. Join in the round. Work in garter st for 6 rounds. Continue in st st. After 23 cm, bind off 8 st in each side (under the arms). Continue knitting the front back and forth. One shoulder band: Knit two rows st st with 14 st. Cast off 1 st on each side = 12 st. Continue in st st for about 16 cm. Break yarn and cast off 22 st for the front. Knit the other band the same way. Then knit the back: Start knitting one row with 50 st, cast off 2 st on the next round = 48 st. Continue in st st for 11 cm. Cast off 24 st for the neck opening. Knit about 1 cm on each band. Join the shoulder bands together using kitchener stitch: http://www.youtube.com/watch?v=I7jIzwO5Nv4
Weave in ends and crochet around the neck and arm openings.