Leos could be 40 grams in pretty shrt time roughly 3 most would be on thw quick end. They attain most of thier growth by 8-12 months of age but can grow a good amount till 18-24 months old. Anyone could correct this if its needed.
Agreed. Some geckos are just going to be larger than others depending on their genetics, feeding. and husbandry. I think it is safe to say that most leopard geckos are considered 'full-grown' at approximately 10-18 months of age. In regard to breeding, males should be around 9-10 months and at least 40 grams and females should be 12 months and at least 50 grams. The more mature a gecko is, the risks of breeding, egging, and recovering become less. You will get more fertile clutches, and they will bounce back faster between laying eggs.