As others have indicated here, it really depends on your 7yo's stroke skills. If they can swim a real lap of freestyle with breathing, they should be able to join a stroke-and-turn clinic (there are multiple sites in Montgomery County, and Martin Luther King in particular is not too bad to get to from DC depending on your location). If they cannot swim a lap, then more lessons are the way to go, whether with a winter swim club that has a developmental program, a private swim school, an individual teacher, or a city/county program.

I firmly agree that starting with summer swim can be a great first team experience for a young DC (and probably for lots of others, too). It helps acculturate them to some of the habits and behaviors of swim practice and meets, but with a hefty dose of friends and silliness. Some folks would call it less serious (it doesn't connect to establishing a competitive record, since the times don't count for USA Swimming). I'd certainly call it much, much less formal, although I do think our team accomplishes good things with the kids. But to me summer swim helps bring a different balance to the year and keeps my kids connected to a community I really value. Part of the reason my DCs are willing to work in the winter is so they can get ready to really enjoy the summer (faster times = more meets = [to them] more fun).

So get your 7yo in front of someone who can evaluate their strokes and endurance, and then you're literally off to the races! It's a great sport, OP, and I hope DC thrives.

At this point I'd look for local classes - maybe your local Y chapter will have some? You probably don't want to commit to anything bigger until you get a better idea of how she gets into it. As the other poster mentioned, there are several montgomery county pools (Bethesda, Long Branch, etc) who don't have a waitlist and have open tryouts every season.The parent meeting for those is typically at the pool the tuesday after memorial day.

I will point out that the Bethesda team is in division B, so there are likely to be some very fast swimmers there. Your child as a walk-on with no previous competitive experience may not swim A meets (but also as a 8 and under there might still be a lot of space for them, I don't know how deep their bench is at that age range, as their top 4 8U girls are all 8, so they will swim as a 9-10 next year)

Join the Bethesda Barracudas this coming summer! They practice at Bethesda Outdoor Pool and are a county-run team in the Montgomery County Swim League (MCSL), so you don't need to join a local pool. That's how my son got started. It's a great team and experience. He was hooked on the sport after his first season and now swims year-round PVS team.

DC Waves might be an option:

https://dpr.dc.gov/page/dc-waves-swim-team-information

http://pvswim.org/pvs_club.htm

Here is a list of local club teams (ignore AU and GW, those are literally the University teams it looks like, but NCAP has an AU practice site). Potomac Valley covers the DC metro area. Look at the list for clubs with practice pools near you. I think Sea Devils is common for those in NW, and as mentioned, some NCAP locations may work for you.

Lots of good advice above, work on skills/strokes now, summer swim, and keep an eye on the clubs that are feasible locations for you, most will have tryouts over the summer.

I'd work on finding a developmental program or private lessons so she can work on getting her strokes to be mostly legal before the summer season. She doesn't have to start now, but it would be good to do at least one session of lessons right before the summer season starts so it's less overwhelming.

I'd also sign up for a summer swim team.

I second the recommendation to have your DD do summer swim and if she enjoys it sign her up for tryouts at a club. NCAP has a program at AU that is really good and they have a 9 and under group. Tryouts are usually in June/July. NCAP AU also has a developmental stroke school and registration for the winter session opens in a few days if she wants to get in the water now instead of waiting for summer.

Can you join a pool near you for the summer? One that has a summer swim team? That's how we started, the kids ended up doing year round swim with their friends.

I have a 7 year old who loves to swim and I think would enjoy it as a competitive sport. We live in NW DC and I am looking for direction on how to get her started. The only place I’ve seen this offered is through dc rec and it’s impossible to get in bc it fills up so fast. Are there clubs or teams we can start with close by?