It's hard to determine the age of Greek tortoises, so you're better off going by overall health and size. If your tortoises are about 6 inches in length, feel heavy, and have been cleared of health problems (worms, runny noses, watery eyes, etc.) then they are probably all set to breed. Since your male is already showing breeding behavior, it probably won't take long. Make sure you have a deep soft, bedding or digging box for your female so she has a place to dig herself a nest when she's ready to lay eggs.