I am in Australia rather than the US, but my approach was that since I placed my kids amongst an older cohort, it was only fair to give them the same freedoms (within legal limits for drinking and for driving), so they would have the best chance to succeed socially. Due to the necessity of working long hours when I was a trainee specialist, my eldest spent 50 hours a week in long day care from the age of six weeks so by her fourth birthday, she had the global development of a six year old and she truly was indistinguishable from her grade peers. The added bonus was that since she was assigned to compete in her age group for sports, she was swimming, athletics and cross country age champion at her school which brought a lot of social credits. She started dating a classmate when she was 14 and exercised excellent judgement as her first BF is now my son in law. They are in their mid twenties and she has a year to go to become a fully fledged general medical practitioner and after a series of well managed projects, he has been selected to become the next state director in a mid-sized engineering firm.
My youngest was also an early school entrant, but with a different birthday, the gap between her and her grade peers wasn’t as large. As the baby of the family, however, she wasn’t as socially mature, but her older sister guided her through the potential pitfalls. She was/is extremely tall and was taller than all her older classmates until the boys reached puberty. She started dating at 16 and our entire extended family adored her BF. We were all as crushed as he was when she broke it off, but she told him she was too young to be in a serious relationship. She is currently the youngest residential student on her Uni campus (first semester starts in Feb here, rather than Oct in the US) and only just recently reached the drinking age of 18, so there was a large turn up at the uni bar to see her sip her first cocktail.
My son is my middle child and he didn’t meet the social expectations for an early entrant (ie. he did not always follow instructions), but his birthday placed him amongst the youngest boys in his grade. He was radically accelerated for maths (declined the offer for science) and participated in many activities (eg. robotics team, martial arts) with older students, but because of his exceptional abilities, he was always greatly respected by older peers. He was the only one of my kids who was legally permitted to drive whilst still at high school and we got him a cool new car so that he and his younger sister could enjoy that particular high school experience of independence. He had a very cool reputation whilst being a geek at heart, so the teachers loved that he made the school a more inclusive place as he was the school’s star athlete (state level at many events) but spent lunchtimes either in the library playing chess or in the music building, playing the keyboard or guitar, so for a while, everyone mixed together.
