Really, how a character is revealed and released is pretty inconsistent. iirc:
- Joker was revealed at The Game Awards, and then shadowdropped on release.
- Hero and Banjo & Kazooie were revealed during E3, and had a Sakurai Presents at a later date.
- Terry was revealed during Banjo & Kazooie's Sakurai Presents, and didn't even have his full trailer until his own Sakurai Presents
- Byleth wasn't revealed until his Sakurai Presents.
- Min Min had a guessing game for months before her reveal within a Sakurai Presents.
- Steve had a reveal out of the blue in a technically not a Sakurai Presents before actually getting a Sakurai Presents right before Minecon.
All that's certain is that there would be a reveal, and an explanation. These could be separately, or at the same time, they could happen whether the character is ready to show in-game or not, and they could happen at basically any time for any reason. There's very little you can actually rule out in that regard. Which of course, also means there's not much you can reasonably expect either. Hence the perpetual "it's this week, I can feel it" this thread experienced earlier.