G'day Tom,
I purchased juvies of these fish over a year ago,the male grew quicker than females, although a pair did breed at a surprisingly young age.
Pearl scales 'developed' (intensified) after a couple of months and just continued to improve.
I have since purchased a group of 10 adults for my pond(they survive year round in there), some of these fish are 10inch+ long(1 dominant male must be 12inch-huge) and stunning colour and finnage.
My original juvies are also growing well and would be 6-7 inch plus with great color.
These fish have a lot more RED in the finnage than the Large colony.
sorry I cannot be more specific in regards to your question, but I'd say from my experience given the right quarters, food(NLS/Hikari/frozen Bloodworm,Brineshrimp in my case), reasonable growth and color can be achieved in months instead of years.
And colour and appearance just seems to improve with age.
I recommend getting some of these beautiful fish but keep in mind they grow to impressive sizes so appropriate quarters will be required.
cheers