[Julie W]

My Office Button / Word Options / Save / "Save files in this format" is
set to: "Word 97 - 2003 Document (*.doc)", but every time I create a new
blank document (Office Button / New / Blank Document / Create),
[Compatibility Mode] won't kick-in until I after I save the document in the
legacy format for the first time.

Excel and PowerPoint don't behave this way: If you've got your default save
format set to the legacy formats, anytime you create a new workbook or
presentation, you're automatically in [Compatibility Mode] when you create a
new workbook or presentation.