I use a Automatic tag "00New" (Zeros sort before letters)
AND I have a "Last Edited" Date custom Date column that gets filled AFTER I "fine tune" the book (or I, again bump the date to Today when I make another change to a book).
I use those in combination to help keep track of which need to be "tuned" and/or (re)sent to my reading device.
I later remove the 00New tag when I find it no longer useful.