The sooner the better!
In Sweden we like routines, or rather we love them and live by them from morning to night.
The same goes for brushing our teeth. We brush morning and night as part of our routine. In fact, children do as they are taught and many of their routines from childhood stay with them throughout their lives. This includes tooth brushing.
research has shown that children who establish good tooth brushing routines have better oral health than others even later in life. Hence, it is very important to establish, teach and accustom children to brushing their teeth as early as possible so that the habit then becomes ingrained. If you are careless from the start, there is a risk that the bad habit will follow you throughout your life.