I had 2 males which simply grew bigger and faster than my other males and didn't start breeding until 3 years old and 2 kilos. But then they both bred consistently and fathered a clutch each.

I have other smaller males that have been great breeders from about a year onwards and one that has taken 2 1/2 years to figure it out. He's only about 1 kilo.

I think it depends and some males just get bigger than others.