Well, in my state, we don't legally have to register her for school till she is 7. Which is the compulsory age here.
If, for some reason, she has to go to public or private she can't legally start kindergarten till 2018-2019 and 1st grade till 2019-2020, per state law.
I have been doing some school like things with her. Just not formally or consistently. She can read short vowel cvc and cvcc words, some long vowel ones and some others. She reads Bob books and working on McGuffey primer. A couple minutes a day. She picks up concept really fast, especially number related. Developmentally, she isn't ready for formal writing nor is she that interested.
She is a very active and physical (4yr old) kid who would rather play all day with other kids. She isn't ready for hardcore formal schooling or sit down work.
I'm really conflicted. She wants to know and understand everything.