Which are you looking for, cognitive, speech or motor skill development? Different things.
Call Early Intervention. If you can't find the number, contact your school district's special education department.
EI will do a full evaluation on him, let you know where he is "behind" and if his delays are severe enough, will let you know what services they can provide you.
In general, though, from what you've written and based on my own experience with my boys (all three receive services) he's not that far behind.
Encourage him to wave..wave to him, help him wave and show him how. Same with clapping.
Label everything and slow down your own speech. Encourage him to repeat what you say, breaking words down and speaking in two word phrases. (by the way, it's still early for speech) Don't use baby talk, use correct words and articulation.
Play, play, play.
at 3:58 PM on Apr. 2, 2009