Swimming lessons are available from 6 months, but i suspect they do not learn much there or at not any more than just taking them to play in the pool. When will they benefit from swimming lessons more than just playing.
The objective of the swimming lessons is so that they can play safely in water and also if they fall in somewhere they can get out on their own.
They benefit starting at an early age by having water be a natural part of their life. If water / water sports / boating etc is a big part of your life, having them comfortable with water is a good thing.
The downside is, having no fear of water, until they do learn to swim they are at risk because water is a fun thing that they are not careful around. A toddler losing their balance on land bumps their butt on the ground. A toddler loosing balance on a boat..... not good.
I love being on the water (sailing), and renting a cottage in the summer is a tradition. As such I got my kids involved in water activities early. That said, I wouldn't say that swimming really became a thing that they had the strength or coordination to do well until they were almost four, and didn't have any confidence in their ability to be safe around water until they were at least 8 or 10.
My kids have both had/have 1-on-1 lessons with a good swimming teacher, who would not start teaching them until their 4th birthday when he considered they had the strength to be able to swim unaided.
My eldest was about 6 before she was confident in the water without any swim aids.
We made sure to acclimatize them to being in the water from babies, which helps them when the time comes to learn to swim.
Apparently, there are two other things to consider:
Babies that are young enough will have a reflex that prevents them from swallowing or breathing water so they can be exposed and submerged without danger of a bad experience. Babies hold their breath
However, apparently, a chlorinated pool will have fumes close to its surface that damage young babies' lung tissue.NIH research on babies in pools
In my opinion, the eailer the better. Living in FL. water is everywhere. children and toddlers that have been taught to hold there breath, to remain calm, and to reach for the side of the pool (or boat, or shore, or whatever) are going to (opinion again) have a much better time if they accidentally fall into the water and start freaking out.
With that said, that does not mean it's safe, by any means, to leave a toddler unattended near a source of water. It just means that if/when they do fall in, they have a better reaction. It's far eaiser to help a toddler out of pool if they are calmly hanging on to the side of the pool, then if they freaked out, started crying, and sunk clear to the bottom.
Another factor is proximity to water. If your life style is not going to involve water activities. Then there is no need or benefit from them being accustomed to pools.
All my siblings, my self, and related children were taught to "swim" by holding on to the edge of the pool, no too long after we started to walk around freely.
It actually depends which kind of lessons are available. My baby girl who is now almost 3 years old have been taking "swimming" lessons since she's 3 months old. We bring her to a private pool in the surroundings each Saturday and she gets a private lesson during 15 minutes, without us being in the pool.
In the early stages, the goal is "survival": teach the baby to fall in the water from various heights in various positions (sitting on the poolside, head first, ...) and recover a safe position, on her back, floating for at least 4 minutes. How long this stage is depends on the child, from a few months to a year the teacher said. It took my girl 6 months I think to get her "diploma". Then the process slowly evolves towards what begins to look like swimming movements, but as baby this age don't master all of this nor understand everything they're told to do, this is basically a very repetitive training.
Here are some videos of her during the lessons. The older ones, at the bottom, show some examples of various exercises in the "survival phase". The newer ones, to the top, show some examples of exercices of "real" swimming.
Note that the teacher (and his wife on some videos) has several years of experience with babies, this pool was created by his father who was also teaching kids to swim and is very renowned around here so I didn't look for any other "qualification", which would anyway be useless to you as I live in Belgium :-) I say this because this is definitely not something we could have taught her ourselves, you need a lot of experience to know what to do and when the baby is ready to go further in the "cursus". We are very glad we took her to those lessons, she's really enjoying it, it could be a lifesaver, and it's anyway great to be able to play in the pool with your child on occasions without her crying all the time because her face is wet or so :-)
Both of my kids started when they were four months old. We have a pool, and I absolutely wanted to be sure that my kids are comfortable in and around water and know how to get out on their own if they fall in. And that's specifically what early childhood swimming programs do (at least the one I'm going to).
This past summer, my 3.5 year old did fabulously in the pool - he was swimming all on his own, without needing floaties or a life jacket or anything like that. He's still too young to use the pool unsupervised, obviously, but I have peace of mind knowing that my very young son can handle himself in the water.
