Sometimes, there are early indications. Timmy displayed his male organ at nine month's old. Both my tortoise had longer tails that wrapped around to the legs. at a pet store, there was a female tort that had a short and stubby tail. The male has a protective shell that covers shields his...
Look at the tort's tail, if it has a longer tail that wraps around to leg, it is a male. Females have short stubby tails and their tail does not wrap to the tort's leg.