You should start flossing your child’s teeth as soon as two teeth touch each other. As they develop dexterity, you can help them learn to floss. Find ways to make this fun for them, and it will help them to want to floss.  Show and tell them how important it is for their dental health and floss for them regularly until they’re able to do it themselves. Use floss that doesn’t hurt their teeth and is comfortable on their gums.