Sharing this because I’ve never heard anyone else mention it; Nintendo never lets their 1st/2nd party release schedule have less than one title with a slated release date in the future. Since we are approaching the release for Princess Peach Showtime, a Nintendo Direct with 1st/2nd party content is imminent.
Of course, they may release a Direct sooner than you expect, but this general observation seems to have applied at least for predicting the latest time frame by which they will run a Direct. And on several occasions, the Direct has coincided with the same month, or the month prior to, the last title with a specific release date on that schedule being released. Maybe this is underwhelming, but I find it useful.