Retrieving an accidently deleted notes folder well after 30 days
If you haven't got backups of your device, it is very unlikely that you'll be able to retrieve these notes after 8 months. If you've left the device on the shelf, powered off for those 8 months, there's a slim chance - but if you have used the device, it is extremely unlikely.

You'll have to take the iPhone to a lab that does recovery from the flash storage devices on iPhones. It will be costly, and there's really only a very, very slim small chance that your notes can be found again.