Most children will be ready to start potty training between 18-24 month old but there's no exact rule. Every child is different and the time when they learn how to control themselves will also differ from child to child.
First, you must try to work out when your child is ready. Observe their toilet behaviour. How long do they stay dry? How long do they keep a clean nappy and are there regular times when they do so?
Below are a number of indications that your child is beginning to gain bladder control:
They know when they have a wet or dirty nappy
They become aware when they are passing urine and may tell you
The gap between wetting is at least an hour; if it is less than this they are probably not ready to start potty training
They know when they need to pee/poo and tell you in advance of an accident
Potty training is usually fastest if your child is at the last stage before you begin. If you start earlier, be prepared for a lot of accidents as your child becomes familiar with the process.
Before commencing potty training, ensure that everything you need is in place. Give your child time to get used to the new tools they will be using. Let them see you fit their new Family Seat and explain what it is for. Ephasise how the rest of the family will be using the Family Seat as well. Show them the door hanger and potty training chart, talk about how these work and put them up in the bathroom together.
Tip: If you have an older child, let your younger child see them using the seat. There can be positive physiological benefit to the advancement of the potty training if you let your child see that other people are using the Family Seat as well.
Once you have fitted your family seat, avoid the temptation to plonk your child onto it stright away, unless they ask for it of course. You cannot force your child to use the potty and doing so will probably upset them, making potty training longer and harder. In time, they will want to use it and until then, the best thing you can do is to encourage the desired behaviour.