MJR10, the measurement is not necessarily taken from the plunger hole. The center of the plunger hole can be used as a reference point for the centershot. You will need to get a 90 degree scale for the nock measurement. I would start at 1/4 inch above 90 degrees as measured from your arrow rest,. Then make a mark on your string with a marker. Then put an arrow on in the middle of this mark and then put your string nock above the arrow nock. If you use a bottom nock (I would use a cushion button), then make sure you leave about 1/8" under the nocked arrow, in order to give it a little room when you draw your bow back.