Wow I'm not sure what already happened or not in this timeline, but this fic has a lot of Kingdom Building and Army Building potential.
With his devil fruit he can make floating islands, so he could save Ohara and their knowledge, recruiting Olvia (Nico's mother) and Nico Robin herself.
He could befriend, recruit future powerhouses and poach them like Shanks, Mihawk, Law, Ace, Sabo, Kuma, Urouge, Jewel Bonney, Tom the shipwright, Sun pirates (Jinbe), the Giants, the Drawves, Minks, people from Wano, Kuja (Hancock and her sisters), Capone Bege...
Or convert future enemes into his crewmates like Gekko Moriah(aftee his crewmates were massacred), Vegapunk, Caesar Clown, Basil...
He could also follow some people to get their future devil fruits and take them.
There are so many possibilities!! I'm really excited about your fic.
Personally I prefer daily chapters (or at least regular) even if they are short chapters so I don't forget the details of the story. I read many fictions and I m always more invested in the stories I know I get to read daily.
Thank you and keep writing!