Is a bit chancy, you'll either go under which could cause the nut eventually come loose, or go over and mess up the thread.
If the thread was good i would've said it'd be okay but because of the known sprocket nut issues if i were you i'd try and borrow a torque wrench from someone.
With the new 12mm nut it's meant to be 90Nm, although i did mine to 80Nm, as a few others have as well.