>>51754280UBs were revealed pretty far in advance (Nihilego was the first to be revealed, followed by Buzzwole and Pheromosa in September)
I don't think they'll ever go as hard on the reveals as they did with Sun & Moon's promotional cycle again though, so it's probably not the best frame of reference
I don't think SwSh or Arceus had anything directly comparable to UBs or Paradox Pokemon, but important late-game mons like Eternatus or Dialga / Palkia's Origin Formes weren't shown beforehand at all and were only known through leaks
