When will Note History actually start recording history?

[Inggrid 0]

I accidentally overwrote something and am considering upgrading to Premium in hopes of recovering a past version of my note via Note History. Will this past version be available, or will I only be able to access the changes made to my notes AFTER the upgrade?

[s2sailor 2,183]

Evernote history snapshots are taken "about" every 8 hours or so.  There is no defined interval other than several times a day.  If your note was sync'd and not in a local notebook and if the changes occurred some time after the original note then there is a good chance the earlier version will be available.  Might be worth a one month's premium upgrade to give it a try.