In the case of using diapers, the moment when you can try to give them up may be already in the 18th month of life? 18–24 months is taken as the moment when the child is able to signal in advance that he wants to pee or poop. However, I think: the moment when the child learns to signal physiological needs in a clear way and strives to use a potty or a restroom.
When is the baby ready?
Some supporters argue that the child signals physiological needs from birth, and the parent's task is to correctly recognize the signs of impending pee or poop. However, if we diaper the baby from birth and want to un-nappy it as standard, we pay attention to some important conditions.
Your baby may be ready to remove the diaper and start Potty Training:
our communication with the child is so advanced that we can expect him to fulfill the request, follow a simple command and will be willing to cooperate,
the child pee at longer intervals, has a dry diaper for 2 hours or longer,
when the baby poops in a diaper, he demonstrates it in some way (e.g. hides behind a potty chair),
the child reports that the diaper is dirty,
the child can be placed on the potty or restroom, tries to do something about it.
Even a few weeks are spent on learning how to empty the diaper, but if we want to completely abandon the diaper? also while sleeping? this may take a little longer.
It is also worth showing and reading thematic books to the child (we have? I can do it. About success on the toilet? Maybe you can try Potty Training With Ladder?). In resigning from a diaper, it all depends on the positive attitude of the child to this change, so it is not worth stressing and nervous: emotions are transferred to the baby and the result may be counterproductive!