If it's not pipped yet, then it will be fine to leave the auto turner on. After pipping it will still be a while before hatching (anything from a few hours to a couple of days... more often than not it's more than 24 hrs from pipping to hatch).
Just keep an eye on that one egg for signs of pipping & zipping. Once it starts to zip, that's when I'd turn the auto turner off if you're particularly worried about injuries... likely to be close to day 18 for the others then, and you can always quickly manually turn them if this first one speeds up a heap.
If you have a type of turner that allows you to take this egg out of the turner & leave the others in a turner (row style) then I'd do that instead.
If it's flopping about after hatch on the other eggs it won't affect them adversely... it'll cheep like crazy wanting company & the rolling about will encourage the others to hatch. The only thing I'd keep an eye on is that if none of the others are showing signs of pipping by the time this first one dries out, I'd keep a close eye on the amount of poop (and therefore bacteria) building up in your incubator.. but let's not worry about that until this one makes an appearance in the world as you may not have to worry in the slightest.
I understand your concerns about injuries... I frequently forget to count the days as day 21 approaches (earlier for my Jap quail) & often don't turn the turner off until I hear chirping. Twice I've come home to Jap quail hatched in an incubator... first one I ever spotted like that was like a toy... sitting upright in the eggshell like some sort of wind-up toy. I've never lost a chook that's hatched in the turner (not that I never will.. and I always check for chirps each night nowadays) but have lost a Jap quail chick that got stuck under the mesh at the bottom of the incubator & drowned itself.. poor little fella.