I have been selecting 'Update Later' option. But then connecting the device and deleting the update files, because last time this happened I accidentally turned it off and it updated when it booted up! lol
Its a pain.... I wonder if Nicklemenu can be used to delete these files?
BEWARE: I just found out if the update files are on the kobo and you don't delete them before ejecting the kobo it will run the update