Give your child the reassurance that it is all right to make a mistake. That is why it is advisable to use a waterproof layer to protect your child's mattress, because you can't possibly clean the mattress. You can air the mattress once in a while by leaving it bare without a bedsheet or sun it out in the open. As a parent, you can do many things to encourage your child. Praise is very important and helpful to encourage your child to learn and keep on trying even with the occasional mistakes.
Some toddlers feel discomfort sleeping with a nappy.
This is the signal that they are ready to begin night bladder control training. A child may show initiative for night training by asking you permission to sleep without a nappy. It takes at least one month before bladder control can be achieved for the night. Buy a waterproof bed sheet to lay the bed underneath your child's normal bed sheet. It is uncomfortable and hot to sleep on plastic, so you need a regular bed sheet over the plastic one.