@elinternational We waited until 4 to do preschool with my older kid, who was also very precocious and shy. We did a co-op that was three days a week and
very play based, almost no academics at all because he really didn't need them...he was reading things like The Boxcar Children independently. It was....fine. He did have a hard time at drop off for a bit, but he had fun and liked his teachers. I liked the co-op aspect where I helped in the classroom sometimes.
That year was interrupted by Covid, and in the fall when it was time for kindergarten, I wasn't comfortable or happy with any of the options. In the end we chose to homeschool and we're still going strong! My younger kiddo is 4 now and we are not doing preschool outside the home with her.
Here's the thing, everyone talks about the social and classroom-behavior aspect of preschool, but if your kid is shy and introverted, there are plenty of ways to get them what they need for social interaction; it doesn't
have to be preschool. Storytime and other programs at the library, swimming lessons, dance, martial arts, soccer, baseball, basketball, scouts, 4H, etc, are all opportunities for your kid to learn to follow directions, stand in line, be a good listener, deal with separation, etc, plus they're around other kids. Homeschooling playgroups have connected me with other families for more informal activities like playground hangouts, playdates, cook outs, etc. For our family that has been plenty.
Obviously, some kids really want a lot more social interaction than that, and then preschool is great! But if you genuinely don't feel that it's best for your kid, it isn't necessary. You'll just need to be deliberate and consistent about providing other social/classroom opportunities.