If you're potty training because you decided to do it now, that's a very different situation than training because the child shows signs of readiness. And it will take longer if he's not interested yet, perhaps only a few weeks if your son is "almost" there, or maybe a year or more.
When a child is truly ready, meaning the bladder and bowel control are developed enough, the nervous system keyed in well enough to recognize the signals in time during play or other distractions, and the emotions are mature enough to accept the ongoing obligation, then a child can often decide for himself he wants to be out of diapers and is successfully trained in a matter of a few days. For most children, this will happen somewhere between 2.5 and 4.5, with boys tending to be somewhat later than girls. When a child is really ready, success itself is the reward and no charts or bribes are needed. They are as excited about it as when they learned to walk.
At this site (http://www.parentingscience.com/toilet-training-readiness...) you'll find some helpful readiness checklists. There are also discussions of different approaches to potty training, the optimal ages, the pluses and minuses of each approach. You might see your son and your parenting style well represented in one of those systems.
Good luck!