Honestly, it's been so long since I've had to adjust z-height, I don't have a guess for how far you need to go.

The way I like to do it is to just start a print on something like a cube and play with the live z adjust until it looks nice and smooth. IMO, it's better to be just a little too high rather than a little too low.

That's really just to make sure your prints stick properly to the bed, honestly. I found that the best way to tune it is by tuning the z-offset (just hold the button during the first layer) while printing a large-ish cube, with the fill angle set horizontally (not in front of a computer at the moment to give you more specifics). It basically is a larger version of what happens at the end of the built-in z-offset calibration.