deadline for potty training   

Researchers have found that those children who have begun potty training at 18 months are generally not fully trained until 4. Whereas those kids who have begun training at 2 years are generally fully trained till 3 years. Many kids may not be fully trained until 4 years. You can wait for a few more months and then consult a doctor. But there is no real deadline; different kids may take different times. Most kids are potty trained by 5 or 6 years. If it worries you, then consult a paediatrician.