Intro
Per the English-Review of Religions of September-1915 (see page 355) an Ahmadi was living in Kampala, Uganda by the name of Fazl Din, he was a Veterinary Assistant. This Fazl Din mentions about Eid and how many people showed up and he asked them for money to send to Qadian, then he tells us that the British government has given the Ahmadiyya Movement 4000 acres of land to use for a mosque. September-1915, pages 350-357.

1927-1928
Commander Dr. Abdul Latif is sent as a medical missionary to Uganda and Kenya, basically East Africa. The other one was Major Dr. M. Shah Nawaz Khan (1899–1977), he was the pioneer Ahmadi Muslim medical missionary to West Africa.

1958
Per Ahmadiyya sources, “Our Foreign Missions” (1958) there was already an Ahmadi mosque there in Jinja, Uganda, it seems to have been built in 1957, there were 2 additional mosques that were built in the same time frame, they are both in Kampala.

Pics

Ahmadiyya Mosque – Jinja Uganda

Ahmadiyya Mosque and Mission House in Jinja