you're supposed to be 6-7 but if you failed once it could be 7-8 it all depends. (when is their birthday, did they fail, and did they start school a year late? these are all important questions.)
Research has shown that boys in general should definitely get a "late-start" in the first grade. For girls, it doesn't seem to matter that much. Boys maturity is slower. "High-performing" males...