Well that is weird. Every IB peafowls I've seen could be identified as males or females when they are months old, especially almost a year old at least. No need to wait for them to be 3 years old to tell the difference.
These birds are both almost 1 year old :
Peahen ...
What DAS said is right. An immature peacock will look like those two you posted, the blue ones, well, other than that, the barrings on the wings are proper to a male, the peahens do not have this, and so you can tell whether the immature bird is female or male, at that age, that is. Of course...