Hi L.,
We started using time-outs with my daughter and son at 15 months. We use the corner behind our front door. There is nothing to look at or play with there, so it is no fun! My daughter would just sit there, but my son is another story. He is 21 months, and sometimes I have to stand right there and make sure he doesn't get up and walk away, but I ALWAYS stand with my back to him, so he knows that he has done something wrong. As soon as my kids have done something very wrong (ie, hitting someone, throwing a toy at someone, biting, etc.) I say that we don't do that because it hurts and gives owies and isn't nice. Then, I put them in time-out. Afterwards, we sit together in the time-out spot and "talk about" what has happened and why. My daugher is 5, and our talks are a bit longer. With my son, we just go over it again that it hurts and isn't nice. I have them tell me/or whoever was the recipient of the hit or thrown toy "sorry". Then we give loves and kisses, and I ALWAYS tell them I LOVE THEM, even when they make bad choices.
I also don't agree with putting them in their beds/rooms for time-outs. Their beds and rooms are their sanctuaries. They are their "safe" places. I want them to associate their beds/rooms with good things, not punishments.
I think that by starting time-outs early, you can use it as a loving teaching moment, instead of just punishment. From the time my daughter turned 3, we would talk about good and bad choices to different scenarios. Now, we gently remind her to make good choices, since she knows that the concequences for bad choices aren't any fun. Good luck!
-Shellie
Oh, and when my daughter was about 2 1/2, she started trying to sneak out of time out. So, we would have her put her nose in the corner. (And we still do.) I would have to wipe down the walls afterwards, because she was usually crying, and her nose would run, but it worked for us. If we were somewhere (a store, a friend's house, the park, etc.) I would find a safe place and have her put her nose on a specific spot for her time-out. These are the things that have worked for us!