For babies the biggest thing is getting them used to being in the water and at the pool. You can do that for free at a public swim at a DC Parks and Rec pool. Of course, a class would be helpful for some folks, for a variety of reasons, but it's not really necessary until the kid gets to 3-ish years old.
Source - I taught YMCA/American Red Cross swimming for 15 years, including baby classes
Just be aware that “swim lessons” at this age don’t result in them being able to swim. It’s about getting them comfortable in the water. It will be years of lessons before they can swim independently.
Dresden0913 t1_j2mofh5 wrote
DC Parks and Rec has swim lessons for babies-- $40 for 6 or 8 weeks at pools throughout the city. That's as close to free as I've seen.