As you can see from my posts, I got as close as I could from loosening and tightening the limit switch up top (top z) and been trying to fine tune using the acrylic bed set screws.
From there, I've used the guide of a piece of paper, when it no longer is able to slide under the nozzle, its too close
Then as someone mentioned, bring the bed UP a tiny bit by doing a 1/8th turn on the bed screw, which should make up for the thickness of the paper.
As I am learning, there may be a few other tweaks to make...temperature and speed, etc.