We know that "Flashbacks don't imply narration for the core character" but I expect Jimbe when we get back to the present to apologize to Nami about Arlong, but it was the perfect moment just now, when we realize WHAT did Jimbe do. It would be weird for the flashback to end with Shirahoshi getting draged to the tower or something not arlong-related and then Jimbe asking nami for forgiveness.
Wait, do we know the aproximate date about:
- Ace's shichibukai invite
- Ace vs Jimbe 5 days brawl
I think that Ace leaved Fushia 2 or 4 years before Luffy, so there's no chance for that event to happen now, but for Ace to be elegible for Shichibukai, that means that there was an empty spot.
The Government trying to recruit Ace and Ace fighting Jinbei happened long after this flashback, so it's irrelevant. Both these events happened in the three years before the start of the story.
Anyhow, we know that Kuma became a Shichibukai in the recent years, as Ivankov wasn't aware of his new position. So I suppose that he took the empty spot that the Government wanted Ace to fill. So Kuma became a Shichibukai between 2 years and year and a half.