Potty training success hinges on physical and emotional readiness, not a specific age. Many kids show interest in potty training by age 2, but others may not be ready until age 2 1/2 or even older. And there's no rush. If you start potty training too early, it may only take longer.
Some parents would like to see this process began as early as possible and cut the cost of diapers and /or pull-ups down.