Depends on the child — for fluoride at home, a child as young as one can have a touch of fluoridated toothpaste on occasion, but I don’t recommend a fluoride toothpaste for regular brushing (or something like ACT) until the child is able to spit it out. No particular age for varnish, either…depends on whether or not the child can handle having it on their teeth.
I read recently online that the ADA has now changed its official recommendation for children to begin brushing with fluoride toothpaste at age 1. However, every parent I have brought this up to has balked, saying there is no way their child wouldn’t swallow it. At first I responded that it would be such a tiny amount (as the recommendation is just a smear of toothpaste) but then I had a friend ask me if that was still OK if the child takes a fluoride vitamin, which would have topical and systemic effects. So then when I read about it some more, I read that kids who do take a fluoride vitamin should be careful of further fluoride ingestion like from toothpaste. So confusing!!!
I don’t recommend any fluoride other than what they get from water supply or fluoride tablets if not in their water until the parents say they always spit out the toothpaste so that is usually around 5 or 6. When they don’t swallow I recommend fluoride toothpaste . We do use topical varnish as early as their first dental appointment because we can be sure they don’t swallow by using a saliva ejector !