My son started brushing when I brushed mine and it is a habit we still do. When I am getting ready for work and he is playing, I will say' "Ready to brushy brushy?" Then he scampers into the bathroom, I put the baby toothpaste on his little brush, put mommy toothpaste on mine, and I sit on the edge of the tub next to him, and we brush away. I do the finishing touches for him, then I rinse the brush for him and he does it more.
Mine also loves to help around the house. He loves to push the broom and mop around, and push and pull the vacuum around with me. I enjoy it now, cause I know a time is coming when he will have to be reminded many times to brush his teeth and to clean.