Sorry in advance for how long this response is. This has been top of mind for me lately and my thoughts aren't entirely coherent at this hour.
My son is 4 and a half but we spend a fair amount of time with homeschoolers, because I have joined the Yahoo and Facebook groups and we started going to the scheduled park days, museum days, etc. The groups were welcoming so we started making it a relatively frequent thing. My son can be himself there and we were invited to join in events for another group that is technically only for kids in 1st grade and up (so here he wouldn't technically be eligible for over another 2 years due to late birthday). They knew how old he was, but didn't care because he fit in well with the kids. With all of these things, it depends on who is running the group and what the parent mix is. The point of this ramble is that my son has found intellectual peers in the homeschooling community. Many of them are 3-4 years older, but at least here, in homeschooling communities there isn't a stigma associated with kids playing with someone who isn't in the same grade or isn't the same age, very different from a public school playground.
By law my son isn't eligible to start K for over a year here due to a late birthday, and since he is already pretty far ahead with low tolerance for boredom, public isn't a good fit for the near future. The other options here are just too much of a drive for our family. If he makes friends through school, I want him to be able to play with them after school and in free time. All of the driving would interfere with the social free time for him. Also, as a kid who commuted to school for years, I hate the idea of him spending so much of childhood trapped in a car.
As to how much time to devote to these things... I could in any given week here take my son to informal homeschool events (the drop in park days, museum days, hiking trips, field trips) seven days a week, with several options a day. I struggle picking which ones to go to. I try to go to no more than two a week to leave plenty of time to do things like just play at the playground (not to mention grocery shopping, etc.). We do commit to a once a month kids book club that he really enjoys. We do maybe one or two scheduled playdates per month, but we bump into the same kids regularly at the playground.
One thing I will say is that I have noticed (as Portia mentioned) is my son is a lot more mellow and at ease when his "attention cup" is full. With homeschooling, that cup is pretty full. What that translates to here, is that he is much much more independent when we have spent a ton of time together (maybe he is sick of me!). So even though we are together all day, he spends a lot of time on his own playing. On days when we haven't had much time together, he can be very intensely seeking attention. For us, it is actually more relaxed the more we hang out together. I still go crazy and am exhausted, but it is actually easier on me this way.
Our home school schedule... Well, we don't really have a school schedule. Maybe up to 20 minutes per day of guided instruction in a particular subject a day -- meaning I purposefully leave something out on the breakfast table he might be interested in. When he asks about it, we do it. I.e. leave Singapore Math book out or handwriting practice book out. Some days he might want to do 4 pages, some days he might want to do 4 chapters. I just follow his lead. If he doesn't want to do any, we don't, and when he wants to stop, we do.
Other than what most people consider school, we play outside, run errands, do chores to run house. He plays educational games if he wants to on the computer or can watch some PBS kids or educational tv some days (no screen time until all necessary errands are done or day is shot). For most of the year we have one scheduled sport. We have done swimming, gymnastics, hockey, soccer, etc. But at this point, 1 commitment per week of listening to another adult tell him what to do (where he doesn't really have input on what drills they do, games they play etc) for a block of time is all that I ask. He has had fun, but he is always exhausted afterwards.
Oh, and we read a lot. Aside from just free reading throughout the day, we usually read aloud for at least 2 hours before bedtime. We also go to the library once or twice a week. My son really likes educational books, so the books he picks are often books other people would consider "school time".
We are pretty loose in our schedule, but I still feel like the week is packed. I always wonder how parents of kids who actually go to school all day fit things in.
For an easy to digest format, for next year we are planning...
1 day a week guided instruction in each of 4 subject areas (reading/writing; science; math/coding; & art). Same format as this year, do it as much or as little as he wants. So Monday might be math, Tuesday might be science, etc.
1 day a week sports
1-2 days library
1-2 days per week homeschooling group field trips/park days/etc
Possible addition of 1 day a week lessons in guitar or piano (not sure if ready for this yet)
At least 1 day fully free no plans
We also do things like visit museums on our own, take hikes, visit amusement parks, etc. Lots of field trips scattered throughout our calendar. Things like an annual auto show are really fun for my son (although I admit the auto show isn't my personal favorite, I do enjoy how much he loves it.)
