test

Position the extruder around the middle of the build plate.

Turn the z lead screw with your bare hand until the nozzle is lightly touching the build plate.

A proven way to do this is by touch: when you can't move the paper freely back-and-forth that's when the nozzle is touching the plate.

You don't have to worry about being crazy precise. The important thing is that you're consistent. Just get a feel for the paper. In a few calibration cycles, you'll be a master.