The worst thing you can do when starting on this journey with a stubborn child is begin the process too early. If they aren't ready to start, they will not cooperate. Period. The power struggle will be in play right from the get go and even if you stop and take a break for a month, they'll remember who won this round and will try it again next time. Trust me.
Most children are ready to begin potty training between the age of 2 and slightly after their third birthday, with boys tending to come in later in this time zone. About 50% of boys are trained by age three while 66% of girls are trained by age three. Special needs kids will most likely train later.
Don't try to rush the process by starting when your child is too young. The American Association of Pediatrics reports that kids who begin potty training at 18 months are generally not fully trained until age 4, while kids who begin training at age 2 are generally fully trained by age 3. Many kids will not master bowel movements on the toilet until well into their fourth year.