From Wikipedia lsiting:
https://en.wikipedia.org/wiki/Hyperolius_argus

Under experimental conditions, the time from metamorphosis to the change to a female color pattern took about two months; for a male, the time from metamorphosis to the development of vocal sacs, with spontaneous vocalization and aggression, was about three months.

Also see AmphibiaWeb entry:
http://amphibiaweb.org/cgi/amphib_qu...-species=argus

Males can closely resemble H. pusillus and H. viridis in pattern and morphology but are much larger.
There is a great similarity, possibly reflecting true relationship, to the West African H. guttulatus. A comparison with H. kachalolae and H. pseudargus is made under these species.