At what age do you start brushing the teeth of your children? Do we need to clean their gums before they even begin to have teeth?

Oh! Yes, you should clean the gums and tongue with cotton. You can wet the cotton and gently clean the mouth from inside. It will make the kid also feel good. And as soon as the kid gets even two teeth, the baby should be introduced to brushing. As early you set brushing habit, better it will be else brushing is the thing that kids don't take very kindly to adapting.