I have this code, which was generated many years ago by a great poster on here.
The "saving" part of the code is in a subroutine, but could be in a Module, which can be called from VBA or from an Autoexec Macro.

Sub Backsup() 
    Dim SourceFile, DestinationFile 
    SourceFile = "C:\Data\MyData.mdb" ' Define source file name.
     ' Define target file name.
    DestinationFile = "C:\Data\" & Format(Now(), "dddd") & "\MyData.mdb" 
    FileCopy SourceFile, DestinationFile ' Copy source to target.
End Sub