It really depends on your toddler as to when they’re ready to use the toilet. Generally, it starts sometime between 18 months and 4 years. At about 18 months to 2 years, they may start to notice they have a wet or dirty nappy. Then, over the next few months, they’ll become aware that they need to go to the toilet.
Eventually, they’ll be able to hold on long enough to make it to the toilet in time. Read more about toilet training your child.