I purchased this tooth brush for my daughter when she was 6. It does a great job. After having it for 2 years, it still encourages proper brushing, leaves teeth nice and clean and I love that I has a 2 minute timer so she knows exactly how long to brush. It has a good battery life and after 2 years it’s still going strong. I also purchased the Star Wars one for my 3 year old son but feel the brush is too big for his little mouth. I’d say age 5-6 is a good starting age for the brush.
100% recommend. This brush has greatly reduced any teeth brushing battles.