Just want to add something from a parent of a 6.5yo who is 'gifted' & was reading at 4yo. DS2 was fortunate he had a teacher who was willing & interested in offering opportunities to extend him, BUT DS2 was not interested in being "different" to the other children at school, he didn't really like having extension work & so rarely did it & that did impact his overall motivation in the classroom, because he had learnt (self taught) reading at an earlier age he went to school reading, but I can't say it was helpful, sure he did his classwork/homework quickly & easily & he isn't a child who would misbehave when bored (& I don't actually think he was bored) so he wasn't a challenge to the teacher in class, but he did spend lots of time running errands/taking others to the toilet or even helping other children, in itself not a bad thing BUT despite having opportunity & ability, he didn't want to & as they say "you can take a horse to water but you can't make it drink".
DS2 will be in year 1 next year & the class he has is a 1/2 but it won't be challenging for Ds2 as he is already at 2+ level academically, but I know the teacher & she will offer him challenges, that still won't mean he will take them up.
DS2 has always been a child who does things when he chooses (cruised furniture for 6months, but ran the week after he walked) & does them without 'error'. At 6y5mo he HATED writing & spelling, the last 3 days he has written 3 pages in a journal of his Holidays, I'm talking on 1cm lines (writing more neatly than half the children who were in DS1's year 2 class), & it started like this "On day 1 of the holidays I woke up at 6:00 I sat down to watch TV and I watched Perth Scorchers v Hobart Hurricanes the hurricanes got all out on 140 the Scorchers needed 141 the Hurricanes win by 31 runs then we played Monopoly..." He used the computer & all manner of things around the house to work out spelling, & he didn't have a spelling mistake (punctuation needs some help LOL) It seems with DS2 that 6y 6mo was the point at which he "clicked" with writing as now he is loving it, but he would hardly write a sentance for the teacher, even when she asked him to tell her what he wanted to write so she could give him the hard words (she knew he hates to spell things incorrectly)
Not that I would be able to stop DS2 teaching himself to read, because I didn't teach him BUT I know if I had my time over I think I would be trying to limit the school type learning & get him learning in a different direction because with a child who wants to learn being an early reader is a great thing, but with a child who is happy with their status quo, even if it is well advanced he hasn't had the chance to experience a joy of learning the same way I see it with my DS1.
Just wanted to give some food for thought there... early readers in some personality types isn't an advantage.