K.K.
1st of all Happy Anniversary!!! I have the same problem with my son, who is 2 by the way. What I did to slow down and eventually stop the behavior is just this: When ever he hits he gets a timeout for 2 minutes because he's 2. When he gets the time out you have to explain that he got it because he was hitting. Also telling him that it's not nice to hit other people. He used to get up from his timeouts but when he realized his 2 minutes start all over again when he gets up, he quit getting up. It has worked so far. He's stopped hitting us. It was really important for me to stop his behavior because i didn't want him doing it to his 1 month old sister. Which by the way he has done 3 times now. Since starting the timeouts he hasn't hit anyone, that I know of. Try it, and I hope it helps you. Hitting is very serious and if not stopped immediately it will get worse. Good luck to you.