I had an 'alternative' educational life.
I attended a Montessori school from K-2nd grade.
Was homeschooled from 2nd to 9th (very loose curriculum).
Went to public high school (9th-12th).
Attended a public state-school for college.

I like to think I got a good view of 'both sides of the coin'.

In general, my homeschooled years were focused on 'real world' type skill building, developing and following personal interests, and having fun. We did some 'regular' book-type learning for math/science/english/etc, but never spent more than 3-4 hours a day on it.

Although I spent a fraction of the time on regular studies that 'normal' kids did during grade school, I entered 9th grade in public school at the normal level. I was above-average at Math and English, but struggled with Science. This, I believe, was due more to my personal interests and learning style than preparedness - but who knows for sure.

The biggest benefit from that time period, imo, is that I really internalized how to a) find and develop my own interests outside of school/sports, b) develop relationships with non-parental/non-teacher adults, c) develop strong auto-didactic skills, and d) have a strong base of 'real-world' skills before I was 14 (cooking/cleaning/shopping/fiscal responsibility/etc).

The biggest adjustment from non-schooling to public-school was the amount of time 'wasted' in my eyes. The amount of material were able to cover in a full day at school was the same, if not less, than what I was able to learn by my self in half the time. This led to some slackerish tendencies and a lack of concern over my grades. I did well, but was never a top-of-the-class type of student.

The second biggest adjustment was integrating socially. Not because I lacked social skills (which is a huge misunderstanding about homeschooling in general), but because of my hometown. I'm from a rural area, and my class size was small (220 graduating class from 6 towns). Most of the cliques of people had known eachother and been forced through the same daily routine since they were 5 or 6 years old. It's really hard to break into social groups like that at age 14. By end of Sophomore year I was able to carve out a little group of friends, but the first two years were quite rough. I think that's more of a testament to location, though.

My advice is this: if you are considering homeschool/non-traditional schooling, try it now. Don't wait. At 1st grade your kid most likely has developed some friendships, and probably doesn't care too much about being 'different' socially. Just make sure you have a well laid out plan for developing social skills / maintaining relationships your kid already has. And, most importantly, take time to re-evaluate. I was lucky that my parents were supportive of my decision to want to attend public school, and didn't keep me from making the choice. Also, really pay attention to the social-needs your kid has. I was pretty much fine by myself for a long time, and therefor resisted a lot of 'normal' social activities (sports, camps, etc) from an early age. If your kid is an extrovert and needs those social interactions to be happy, it will take extra work to accommodate.

That ended up being more of a ramble than anticipated, but I could talk about this for hours, so if you have Q's lmk.