Introducing my children to the water and swimming has always been very high on my list of priorities. My oldest entered a swimming pool at the age of 3 months and began an evening Mommy and Me class at 6 months. My second child has also been in the pool since she was an infant. The Mommy and Me class was basic and nothing that I would spend big money on. It was essentially walking and bouncing in a circle while singing kid songs.
In my experience, it takes alot of work to bring young children to the pool. Packing, changing clothes and feeding immediately after. Plus tending to your own showering (although I skipped this for the sake of simplicity), changing etc. My kids were always starving after pool time. The flipside is the great sleeping after time spent in the pool. I would do my best to bathe my child after swimming (not always easy) and put her directly into her pjs. A car ride home and a bottle right before bed was all I needed for a smooth bedtime routine.
Best of luck!