Okay....
Lets try:
Courtesy edit time = 60 minutes should be long enough for most typos to be spotted and corrected. An edit within the first 60 minutes after posting will not result in a 'edited by:' message.
Maximum edit time after posting = 120 minutes after 120 minutes the 'modify post' button will vanish and further edits will require the assistance from an admin team member, i.e:
Warlock, Dougal, Hammerman, Pig Hill Resident, Mr Rusty, Florence, Brunel & Ermintrude (These are in no particular order)
Lets see how everyone gets on with these values, they can always be adjusted again.