Thirty minutes might be a long time to keep a Chief of Surgery from a well-regarded hospital who is strongly advocating for herself waiting.
Miranda is younger than Chandra. Miranda and Callie were in the same class. Arizona was an attending and Meredith, Alex, George, Izzie, and Cristina were interns while Callie and Miranda were still residents. So Miranda may be younger than Arizona and slightly older than Meredith. Meredith was born in or around '78. Having Miranda graduate high school in '92 or even a couple of years later fits with other information we have been given though the run of the series.
Grey's has a mix of actors playing characters older than they are (Amelia, Arizona), about the age they are (April, Jackson, Maggie, Richard, Catherine), a handful of years younger than they are (Miranda, Ben?) and around a decade younger than they are (Meredith, Alex).
Catherine bringing food to Ben and Richard reminded me of the time that she sent snacks (that Cristina enjoyed) to Richard after Adele's death. Also, while I understand that it didn't fit the story they were telling, I felt the visual absence of a Black Lightning/Tucker Jones flashback.