If you create a routine called FileSave (in a standard module in the document or its template - it might depend a bit how the document is being created) it will be run instead of the built in Save command and you can do what you want in the routine, for example ..

[VBA]Sub FileSave()
ActiveDocument.SaveAs "report" & Format(DateAdd("d", 1, Date), "mmddyyyy")
End Sub[/VBA]