I wouldn't sweat it about being late to the game at all. You aren't in the slightest.
If you're working full-time, try some of the after-school enrichment programs. Art, music, steam, sports, etc. TK is young but the school should mention what they offer, usually through a 3rd party that'll charge. It's at the school too, which will become clutch when you have multiple kids doing after-school programs. But, like Swallow Tail said above, pay attention to what it is and above all, make sure your child is enjoying themself. Don't be afraid to pull them. None of this is the be-all end-all of existence.
YMCA maybe having programs? CYO also has stuff too, as far as athletics.
One thing I really liked about baseball (and it's definitely coed) vs. something like basketball is that every kid gets the same chance to hit, field, run the bases, etc. My son really enjoyed little league. Had to swallow the ego a little but even though it was fun, he skilled out. I did assistant coach his team and that last season of fall ball was a lot of fun together - some great memories for sure.
Was also apparent he needed a bit of discipline and self confidence, martial arts is something he's been at going on 5 months and he enjoys it a lot. He only has an older sister and we don't live in a neighborhood that has a lot of kids his age so he isn't getting that roughhousing that boys need. With the martial arts, he does and it is a positive.
Activities away from school are good because they also open other potential circles of friends.
It may/will drive you nuts trying to juggle so many activities but taking the time to be there for your kids is worth every moment. Whether it's recitals, games, chess matches, whatever, being there means a lot to them. Even more so with activities that you can do together, great bonding.
