In a bisexual flower, if androecium and gynaecium mature at different times, the phenomenon is know as

The phenomenon in which the male (androecium) and female (gynaecium) reproductive organs of a bisexual (hermaphrodite) flower mature at different times is called dichogamy. Dichogamy refers to temporal separation of anther dehiscence/pollen release and stigma receptivity, and is generally classified into protandry (anthers mature first) and protogyny (pistil matures first); this mechanism promotes cross‑pollination by reducing selfing [2]. Herkogamy, by contrast, denotes spatial separation of anthers and stigma rather than temporal separation [2]. Therefore the correct choice for temporal separation of maturity in a bisexual flower is dichogamy (option 1) [2].

Sources

1. [1] https://agritech.tnau.ac.in/crop_improvement/crop_imprv_pollmode.html
2. [2] https://mgnv.org/plants/glossary/dichogamy-protandry-protogyny/