In the US our child started going at 6 weeks old. Daycare (and now preschool) is just as normal to her as being at home. Especially since in her three years she’s probably had over a dozen different teachers. She’s learned to warm up to new people and situations quickly.
I also work in an elementary school. (5 to 11 years old). I see kids that didn’t go to school at all before coming to us. Even some are homeschooled for a few years before starting school. I can usually tell the difference between kids who went to some kind of preschool (3-4 year old program, even part time) and who hasn’t. It’s not always a bad thing but it’s a harder adjustment for those kids.