I dont think sex matters but i have heard a few times from people on here that a leo is full grown at 18 months. Some grow at different speeds, for example i had a little guy i was trying to nurse back to health and in 4 months he hadnt grown at all and eventually died, thats what i get for trying to rescue one.
I think it just depends on the gecko. We have Giants that were still growing longer and heavier at 2 years old and a little Patty who stopped growing at around 10 months old.