no right age - it's that simple
it's about whether or not your child, absent of age or sex, is ready
my friend started her boy at 2 - it was, and is a nightmare, and he is now 5
there are signs as to whether they are ready ....
Dr Chou, MD wrote ... "The most important factors are not necessarily age, but rather physiologic, physical and psychological readiness.
Before a child can be "toilet trained", she must have attained a certain amount of physiologically readiness, namely "bladder readiness". In infancy, babies frequently are unable to hold large amounts of urine in their bladder and void small amounts. As a child grows older, her bladder becomes more mature, and is able over time to hold larger amounts of urine between voids. This comes hand in hand then with the additional ability to be able to increase the interval between voids. When you notice that your child is dry at longer intervals (i.e. dry after a nap or for at least 2 hours) and is voiding large amounts at a time, then that is a sign that your child may be physiologically ready for toilet training.
Another component, which overlaps with psychological readiness, is the ability of your child to recognize that she is voiding (i.e. if your child does not recognize when she is voiding, toilet training is virtually impossible). Some children start showing some signs of "bladder readiness" around 2 years of age. Most will attain it by three years of age.
Another component of readiness is physical readiness. This includes the ability to walk well (to and from the bathroom), to be able to pull pants up and down, and the ability to get on and off the toilet/potty chair fairly independently. While this may seem like a "given", think about grandmas who claim their children were toilet trained at 6 months or a year of age. Some kids are not even walking at a year, how could they be toilet trained?
The last component is probably the most important: psychological readiness. Or what I like to call willingness! If a child is not bothered by a wet or dirty diaper, if she is uninterested or unwilling to sit on the potty, believe me, you are not going to get very far. As the saying goes, you can place a toddler on a potty, but you can't make her pee. Toddlers quickly learn that they can control their bodily functions.
Once your child is showing all these components of toilet training readiness, most experts recommend waiting at least three months before you start toilet training to ensure that all is set. This is a good time to "set the stage" for toilet training as well (letting her observe others using the toilet, introducing books or videos on the subject, starting to talk about them using the potty soon).
Last but not least, look at yourself and your family situation. In order for toilet training to be as painless and smooth as possible, make sure that you AND your child are ready. Some kids toilet train quite easily, while for others it becomes what seems like a long drawn out battle. If you are incredibly busy at work, moving to a new house or a new baby is due soon, it's ok to wait a few months to let things settle down. This is probably one of the biggest steps for your child and it's worth it to wait."