At the Magic Kingdom you can find Minnie at the Silly Sideshow. In EPCOT she is always at the Character Spot. In Animal Kingdom you can meet her at the Adventurer's Outpost on Discovery Island. In Hollywood Studios Minnie is always at her meet 'n' greet on Commissary Lane.
Look around, character meeting locations change in location and schedule, I'm sure there are sources for exact times, but it varies based on multiple factors. Most likely near Main St. From opening to mid afternoon
The Disney App is indispensable! Wait times, character appearances, food locations, and everything else you need.
Disney website will give times and locations for character appearances
Download the Disney Wirkd app. You should be able to find where she is at that way.
At the magic kingdom, I recommend down loading the App. It will allow you to see the time and location of all characters.
Character dinning events can be booked thru Disney app or concierge desk. We saw her at contemporary resort breakfast buffet in Chef Micky's restaurant.
Thanks! Your answer is awaiting moderation.