You should check your toddlers diaper at least every 2 hours and change if needed. If partly wet you don't need to change the toddlers diaper right away but if it's very wet you should change the diaper.
As a baby gets older they tend to urinate less. Newborns will wet their diapers a lot enough to need 10 to 14 diaper changes per day.
But a 1 year old will need maybe 8 diaper changes per day and then at 2 they will need around 5 or 6 diaper changes per day.
Depending on how much the toddler wets or how often the toddler poops their diaper.
Make a schedule or set a timer to remind you to check your toddlers diaper at least 1 hour and half to 2 hours.
Don't go longer than 2 hours without checking your toddlers diaper as leaving a toddler in a wet diaper or poop diaper for too long can cause a rash and urinary tract infections.