id hold out a while. i had a common that looked like a textbook female, then seemingly overnight, he was fanning his penis and had a large bulky tailbase and cloaca. now hes a good 6.5 inches, and all male. when i got him he was just at 4 inches. males grow fast, mine when kept outdoors will grow at least 2inches shell length over the spring, summer, and early fall months. once they reach about 10-11 inches they slow their growth, but still grow quite visibly.