When and how to potty-train are very common questions in a pediatric clinic. The cost of disposable diapers or the work of washing cloth diapers is something no longer very desirable to most parents.
The most important thing to remember when approaching potty training is that each child is unique. Deciding when to potty train has a lot of variables, the child needs to be interested, the family needs to be at a point where they can devote some time and attention to potty training, and it shouldn’t be done at a time of big changes or stressors. The child needs to be aware of when they are peeing and pooping and have a desire to use the potty. I usually do not recommend trying before 18 months old but many children are not ready to try until 2 or 3 years old. Because one child in a family was completely potty-trained by age 2 and another is still mastering the skills at 4 1/2 years old, does not mean the 4 1/2 year old is behind.
Toilet-training should never be forced and children should not be punished for accidents. Positive reinforcement is key. Consider a reward system by finding something that your child finds as a reward. Options are a small toy (something from the dollar store or similar) for each time he goes pee or poop in the toilet. You can also create a sticker chart where he earns something (trip to the park, toy, etc.) when he gets so many stickers. Remember to keep the number of stickers needed small or he will lose interest quickly.
Sitting on an adult sized toilet can be uncomfortable for kids and sometimes it can be difficult. You may want to try buying an insert for the adult seat so it better fits your child or a child size toilet. Let your child pick it out so he is excited to use it. They make some with all different characters or colors. They even make travel ones that fold up. If using an insert on the adult toilet, a stepstool under his feet so his legs have support may also help. Some children find the large toilet intimidating. You should stay with your child, maybe read to him, sing, or play a game. The more fun you make the experience, the more he will want to do it. Also finding times when he is more likely to need to pee or poop are helpful. After meals, especially breakfast, is a good time.
“American Academy of Pediatrics Guide to Toilet-Training” is a book addressing all the common toilet-training questions and more. It is available at many local libraries.