Best of luck with the pair you have found,Are they a nice pair?strain?
Females mature quicker,I have had them laying at 7 months,males generally take longer to be fertile,12 months +
Females growth will be strongly inhibited if you let them spawn to young and small
Once they carry fry there growth all but stops,very hard to stop them from spawning though once they start
Only way is to separate sexes even then 2 females will still lay eggs together.
So you potentially could have a viable pair at 12 months+ of age but generally it takes them a few attempts to get it right,if they ever