I did end up using this and it worked perfectly although I had to pay for a month which is fine with me since it's exactly what I was looking for.
I backed up my notes in ENEX files then started on the process.
It had an issue changing the old notes the first time so I made a TEMP folder in EN and set that as the folder that would prepend the date.
Anything I dragged in there took a while but the dates got added. So it's a slower process, but does the job. I did it starting about 4pm my time yesterday and I checked before bed and was only small way into the process, woke up and all done.
This was a small test of 900 notes, now I'll add the rest I need.
For reference, I'm using Evernote Legacy, Windows 10, and Filterize.
The action steps were to pay for account, then go to Dashboard > Filter Manager > create Simple Filter > choose Note Title > Add Title Prefix > click + sign and choose Time Note Was Created > choose the time format I wanted > set condition to In Notebook and type name of notebook > save > drag notes into notebook and wait