You set up a degree wheel and pointer with Zero at Top dead center. To do this, use a piston stop and split the difference from the approach to top dead center from each direction. With the ignition on, you slowly move the crank shaft in the direction of rotation until you hear the ignition fire. Note the location on the degree wheel. From my experience, 28 degrees BTC is my magic number.

The position of the sensor is adjusted to adjust the timing.

By trial and error, you try the timing in several different positions of advance until you find the maximum rpm obtained. You then retard a degree or two from peak for preignition safety.

A note from back up the way in an earlier post . . . . The C-H ignitions I own are not made in China but in Wyoming USA.