We're still waiting on that Minecraft content though.
It'd be very weird if he got wind of a Mii costume or stage all the way back in May 2018, but didn't hear a peep about Banjo.
Well, Oppossum, who I put a lot of personal trust in, says he had heard that Microsoft rights **** was worked out all the way back around E32018 time, which actually makes a lot of sense considering that's when Vergeben originally started saying that ****.
Is it absolutely crazy that they'd have picked a DLC character THAT early in development?
Well, no, not really.
Ultimate was already in a very presentable state at that time and was only 6 months from launching. All things considered, at E32018, it was actually mostly done, this is how EVERYONE got leaked behind the scenes. Reminder, we knew the ENTIRE base roster in AUGUST via leaks, that was only 2 months after E32018, and even still that's only when Verg spilled the beans, other people knew it MUCH earlier but chose not to say anything.
Another thing to note is, after the November Direct, iirc the literal few hours/days/week after, Sakurai had said that the 5 DLC characters were already chosen, meaning that they had, IMO, most likely already secured the rights to Fighter 1-5 by that point.
Obviously, Banjo wasn't worked on THAT early, especially since we didn't have any codename in the base game implying that any work had started unlike Plant, Joker and Erdrick, but it's more than logical to assume that the rights to particular Microsoft IPs were discussed at that time. Didn't Phil Spencer specifically "Go out to lunch" with some Nintendo higher ups at that E3?
And that's another thing.
Thanks to the base game datamine, we know for a fact that yes, DLC was being worked on before the game was finished despite the myriad arguments of "Sakurai said he wouldn't!"
DLC was planned out in advance this time, and considering how quickly Sakurai said characters 1-5 were already chosen, it was more likely than not that all 5 rights had been secured as late as November.
and 
