C.K.
Every parent has to develop their own style of discipline as what works for one, may not work for others, and what some find to be cruel, or too early, may be right on target with others. Sometimes you have to be creative, or outside the box to suit yours and your family's needs. Also only you know your own kid, and know if they're ready for a time-out.
That said, I started time-outs with my son at 18 months old. I too felt the lag time in taking him to the chair was not getting my point across effectively. So, and I hate to announce it, I made him sit right where he was when the action occurred (yes much like training a dog, sadly) and would have him sit down for the full minute or however long it took to get him to calm down. After about a week I moved him to the chair, and after a week of taking him there, all I had to do was say "time out" and he would go on his own. He sees the dogs being disciplined in this manner, and connected that he was in trouble when told to "sit down...time out" as well.
He's now 20 months and finally does not move from the chair unless given permission, he also gives his punisher a hug and kiss, and we are currently working on saying "I'm Sorry" once released. Granted my son has a very broad vocabulary and is already speaking in 3 word sentences, so I know that he can communicate his frustrations verbally rather than physically.
Whenever he moved from the time out position (chair or floor) I started the time all over again till he stayed put. At first though I did hold his hips down when he sat and said(still say) "all done" when the time is up. I was told to put him in his room by family, though I personally didn't want him connecting his room with punishment, but wanted to leave that space as chosen alone time (a personal sanctuary if you will), which he happily enjoys daily.
Hurting mom, and others, dogs included, is unacceptable, and they have to learn not to do it. Just saying "no" firmly doesn't always work for every child, and as they get bigger, they get stronger and it hurts worse. A friend of mine tried the just say no approach and now her three year old hits because she is trying to hurt you as much as you have hurt her feelings. It feels like a ton of bricks, and no one wants to have play dates with them anymore because she's nasty when frustrated.