Apparently in Hawaii, guavas are treated to cause them to bear at different times of the year. I don't know how all this might apply to growing them in Africa but here's a link with more info than I wanted to know...
https://www.extento.hawaii.edu/kbase/crop/crops/i_guava.htm
By changing the suffix in the url, other fruit info is available too. Good luck in solving your problem, please tell us how you made out.
