Hi S.,
Personally I would wait at least a few more months. Babies can start learning to swim, to some extent, but why the rush? Often when children learn to swim at a young age, they are not nearly as self-sufficient in the water as they or we believe. My almost five year-old has been taking swim classes for about nine months, and after just a few months he had caught up with the kids in his class who had started in mommy and me classes years before. I'm sure there are kids his age in other classes who swim at a higher level, but he will catch up (we're not exactly gunning for the Olympic here!). There's no reason not to take your son into a pool now and again to get him acclimated to water, but why lessons? However, to answer your question and put my personal opinions aside, I checked the website for where my son takes swim lessons, and their mommy and me classes start as young as two months. All they do in those classes is sing songs and "create a nurturing aquatic environment" by playing some games, and theneventually teaching parents how to submerge their babies. At 18 months (14 for "more active" kids"), kids can start to sort of learn to swim (still with a parent in the pool). They kind of learn to dog paddle a bit with fins and goggles and they make balloon faces and then put their heads in the water. At 36 months, the kids can graduate to "real" swim lessons. The place has an indoor pool (the pool is used for nothing but children's swimming), though, so sun is not a concern. Also, please keep in mind that babies need the water pretty warm (80 degrees plus) to be comfortable. In the sun, I would put him in a wetsuit looking SPF protection suit. You can find them online. Make sure they specify the level of SPF. The rash guard (short sleeve shirt w/ mock turtle neck)we got for our son is SPF 50. The brand name is Xcel. We used it in Hawaii and he did not get a sun burn. We did not need to apply any sunscreen under the rash guard except around the edges in case it moved.
K.