The below are the spoiler free(already known) events and what time they might happen in my story.
1. Our MC gets transmigrated in bleach world 50 years before the main story starts and goes to the academy 2 years later meaning 48 years before the main story starts.
2. 50–45 Years Before the main story: Rebuilding the Gotei
The gaps left behind by the Visored incident (100 years ago) are fully filled during this era:
Kaname Tōsen appointed as 9th Division Captain.
Gin Ichimaru appointed as 3rd Division Captain.
Sajin Komamura appointed as 7th Division Capt
Soi Fon succeeds Yoruichi as 2nd Division Captain.
Kenpachi Zaraki slays the previous 10th Kenpachi, becoming the 11th Division Captain.
Aizen Sōsuke and Kurotsuchi Mayuri had already been promoted directly to captains (5th and 12th Division) immediately after the Visored scandal 100 years prior. Isshin is still the captain of squad 10.
3. About 45 Years before the main story starts, decline of the Shiba Clan begins due to some unknown reasons.
4. 30 Years before the main story starts, Kaien Shiba dies, slain by Rukia.(may change the year according to the need of the story)
5. 20 Years before the main story starts, Isshin Shiba disappears, abandoning his captaincy of the 10th Division.