This will add a new dimension to the use of e-notes as a means to produce paydata, and will also give a purpose to the metadata that the e-note stores in its memory. It would be used for proof and evidence purposes, i.e. "My ex wrote this suicide note -before- I broke up with her, not after." You could distribute evidence that may disprove accusations against you, or prove your loyalty to someone based on e-note records you kept and made copies of.
Some additional ideas branching off of this: People who have the skill to unlock an e-note could, in theory, hack into an e-note and mess with the dates to make something seem like it was written earlier or later than it actually was. Of course, it will always be possible to delete a note and re-write it again for it to have a more recent date, or just not include the date on the printout in the first place. It'll be an option that you can choose when you print something out.
I really hope that you consider this idea, as it would encourage a more sophisticated way to engage with paydata. Characters could use this option to solve mysteries, drop false clues, or show proof that things were written before other events happened. I look forward to hearing your thoughts on having the option to display the time&date of writing on e-note printouts.