General plasma cutting rule: Pierce high, cut low.
Your pierce height should be as high as possible and still get a valid arc okay signal. It's like dropping a big rock into a bucket of pudding; if you hold your face too close it will get dirty. The accepted method when cutting manually is to angle the torch so the blow-back goes off to one side. With a machine torch that is not possible. By piercing higher the backsplash (which goes out in a "crown" shape) does not tend to clog the tip or shield. The air blowing down will normally keep it below the .125 level.
I try to pierce at .125 to .200 above the material (except for Fine Cut). I have my software configured so that it:
Touches off to get the material surface at the pierce point
Raises the head to pierce height (not cut height)
Fires the torch and waits for an Arc Okay (Arc XFR) signal from the plasma
Plunges the head into the cut to "initial" cut height
Starts movement of XY
Delays THC takeover until voltage gets past pierce event
SheetCAM has provisions for doing a separate pierce height and cut height. If you don't have a way to utilize the ARC GOOD signal (Should hold movement until valid) or your plasma does not have that signal available your cut process will not be as precise as I listed.
I can cut 3 or 4 4X4 sheets of decorative cuts (lots of pierces) before changing tips. I find electrodes outlast tips 3:1 so I buy them in that ratio.