Yes. Yu have to make sure that first of all the baby is very healthy because you never know what may happen with different swimming environment. If the water is not pristine or very well taken care of then babies were obviously much more susceptible to getting ill if they spend too much time in the water. But the earlier that someone gets in the water and builds an association with it, the more confident they become and they become more familiar and comfortable with that environment. It makes it so much easier to teach them. If someone doesn't start until later you actually have to overcome an instinctual and natural fear of the water. We can't breathe under water, so humans don't naturally take to it like the fish do.
