Hello! I have 2 1/2 year old twin boys, and we started potty training them about 3 months ago. We picked the day we were going to begin, and when that day came, we made a big party of it - horns, hats, prizes - you name it. They were very enthusiastic. We took them to the potty about every half hour for the first day. Of course, we had some accidents, but half the battle was just keeping them interested. Every time they would attempt it, we would get so excited and cheer like they had just won the Olympics! They would get a little "prize" just for attempting(goldfish, raisins, etc), a pee got a bigger prize (sticker, piece of candy, etc...) and a poop got a big prize (little car, truck, toy, ). I know some people would disagree with this reward/bribery method. But, we only did that for a few days, then it became a habit. I would say they were fully trained within a week - aside from nights and naps. That was three months ago, and they have done great ever since.
I know that every child is different, so there are never guarantees. I think that the child definitely has to be somewhat interested, but sometimes if you can keep them excited about it, that's half the battle!
Good luck!
A.