The best time to start potty training your son Teaching your son how to use the potty requires a reasonable degree of cooperation and motivation from him, plus time and patience from you. The key to potty training success is starting when your son is interested, willing, and physically able. Although some kids are ready as young as 18 months, others may not be prepared to learn until well past their third birthday. Some experts believe that boys stay in diapers a bit longer than girls because they're generally more active and may be less likely to stop and take the time to use the potty.