From my experience males do not grow faster at juvenile stage. Females growth only slowed down when they start to produce spawn.At what size was he when you could tell he was a male and what specific trait made you sure he was a male? I have some grow outs at the moment, do males grow faster?
As the juveniles grow they all look identical. The only sure way to tell sex is when two pair off. Colours change over night. Mine have paired off at 6 inch. The most important part is rock rocks and more rock. I'm expecting spawn and wigglers from my second male any day soon. Picture of 6inch fish pairing.

