only true way to tell pre ring, besides DNA, is by classic male/female behavioural display, anything else is really just guessing:-
example of male, cobra looking head wobbles, and they hop along the ground tapping their beak also, Kai is only just 22 months :-
example of female, lutino, see her head back position and the squeaking behaviour, more noticeable in breeding season, Mickey is just on 24 months :-
Hope this helps ..
Cheers !