Aptos — 2023 to present
Calibri — 2007 to 2023
Times New Roman / Arial — 1992 to 2007
(I didn't do much digging into the origin date of these earliest fonts in Microsoft products. The history is murky.)
The Microsoft default font (typeface) has been used as an absolute dating mechanism and as a forgery detection anachronism.
Maybe we can use the Default Font to define modern eras, which would be much more exciting than being characterized by a generation. (Generations are so downbeat, boo).
Ironically, the US government has only just this year switched to Calibri.
The rationale behind changing default fonts is pretty interesting; an intersection of patent law, fashion, history, and print/screen technology. Design patents apparently expire after 15 years, so perhaps see you back for the next era in 2038.
A related typographic link are the interesting videos by Linus Boman. This one on Microsoft fonts is a good starting point.