I say have a 5 minute time limit, where you can edit a post without the "Last Edited blablabla" showing up. And then have it where you can edit it at any time, any amount of times, with that message showing up.
It tends to make smaller posts look shitty, and I'd like a chance to correct any spelling mistakes or sentence structures really quick without it showing up. If I wait longer than 5 minutes to edit, then that should be my problem.