I started disciplining my son at 6 months with saying 'no' and moving him away from [x]. At about 10 or 11 months we started counting to 3, and then at 3 give him a tap on the hand and turned him away from whatever it was he wasn't supposed to be touching. If he repeated the action I would tell him 'no' and move him further away and tap him on the bottom (lightly). He got the message though. He's now 14 months old and at 12 months I started giving him time-outs. He generally doesn't get past 2, but on the occasion that he does, or he keeps repeating the offense he gets a time out where I sit him in his crib without toys, with the door open until he is quiet for one full minute (when he is two, it will be two). Sometimes it takes awhile, sometimes it happens fairly quickly. He is a really great kid. I just have to say his name and he stops whatever he's not supposed to be doing, or comes back from wherever he's going. (I know this will change though!) If he gets really bad I ask him if he wants to go to bed and he immediately stops!
After a time out we always make sure to make him laugh and make sure he's happy. I don't want him to think the day is ruined because of one discretion, and want him to know that life goes on with the lesson learned.
I'm going to enjoy this while it lasts, and hope that our continued consistency helps him to understand the things he needs to. I've been told the first child is a ruse! I hope not!