The first day my son in the pool was 6 months old. I think it's better to drop them in the pool earlier than later so they can get used to the water earlier. My son was bit scared when we put him into the water and we even dipped him under the water and he just swim and float naturally. I am not sure the chlorine will do any bad reaction or harmful to the skin but i didnt see any bad reaction on my son. However, the pool was not very clean and i saw a lot of dead mosquites floating on the water, since then we didnt go back to the pool.