July 19, 2012 -- Lily Yeh, of Vienna, Va., plans to get a head start on potty training for her 20-month-old daughter, Peyton, because she says Peyton is ready.
"Whenever we go to the bathroom she follows us; she knows the sign language already for potty," said Yeh. "Those are great indications that she's able to communicate her desires."
Indeed, timing is everything. However, the hard and fast recommendation by many experts to get children out of diapers before age three is a myth, and can even be dangerous for some children, according to one expert.
"Children under age 3 should not manage their own toileting habits any more than they should manage their college funds," wrote Dr. Steve Hodges, a pediatric urologist at Wake Forest University Baptist Medical Center, in an article on the parenting website Babble.com.
Yeh said she read that girls are typically ready earlier than boys are. Also, since she's expecting, she's hoping to have Peyton out of diapers before the new baby arrives.
These reasons are not unique to Yeh. Many mothers to begin training because of a variety of life factors, including the need to have a child potty trained so they can go to day care programs or school.
But preschools and facilities that require children to be potty trained by age three, "are harming kids," according to Hodges.
A child's bladder, which continues growing to its standard size until age three, grows stronger and faster when it's filling and emptying uninhibited, said Hodges.
"When you train early, you're interrupting that process," he told ABCNews.com.
Training a child too early can lead to toilet accidents because the bladder may not be strong enough. It may also lead to constipation, kidney damage and even urinary tract infections, said Hodges, mainly because children are holding in their bowel movements longer than they should, said Hodges.
These conditions may also be signs of forced training, and often by parents who think they're behind the potty training eight ball, according to some experts.
To prevent medical complications, children should be allowed uninhibited elimination until they are ready, he said.
Age doesn't matter when it comes to potty training, according to many experts. Some children are ready earlier than others.
A child's social, cognitive, and physical skill sets should dictate whether a child is ready to train, said Dr. Stefani Hines, pediatric developmental and behavioral specialist at Beaumont Hospital's Center for Human Development.
"At their age, they have control over sleep, eating, and going to the bathroom," said Hines. "So this is one of the few areas of their life they have control over."
Hines said the control should stay with the child. If the child is resisting potty training, parents shouldn't force it, she said.
According to the American Academy of Pediatrics, a child is considered ready to be toilet trained when he or she can communicate their interest in using the toilet, can walk to the bathroom, can dress and undress themselves, and can sit comfortably on a toilet.
"Children are certainly able to be trained earlier than they are ready," said Hodges. "The sooner you have them trained, the sooner you need to make sure that all of this is happening."
Pediatricians often explain the signs to look for when the child reaches about 12 months. But every child's ability to catch on is different, said Hines.
"Parents should not get caught up in the age cutoff," said Hines.
Yeh said she knows Peyton is among the younger children who are beginning potty training, but did not think much about age when considering whether she was ready.
If Peyton doesn't take to a 3-day training method, then Yeh said she plans to continue to try unless Peyton doesn't seem interested.
"There shouldn't be an age mandate is my belief," said Yeh. "I'm very against Peyton having to reach marks by a certain age, because I know that new skills do take time."