Technical - (Trigger Tooth) Simplified

First trigger tooth is just a reference from the angle of the tooth that is pointing to the sensor when cyl 1 is at TDC. 

The simplest explanation of the Primary trigger settings when a missing tooth wheel is used: 

If I were to tell you… "Hey! Tooth "0" is the first tooth after the gap....  when you see tooth "5" pass by the sensor, that means cylinder#1 TDC tooth is going to pass the sensor in "60" degrees, so get ready to fire!"

The example is based on if the fire order is correct in Ignition Outputs and the following:
Missing tooth wheel
First Tooth "5"
Trigger angle "60"

A “Multitooth” primary wheel is more difficult to calculate since the cam is the only reset. If it is a “Multitooth” wheel and the cam is the main reset tooth which is harder to figure out.  Just start with "Trigger Angle" "60" deg, crank it over with a timing light and adjust the "First Trigger Tooth until TDC gets close, then fine tune the trigger angle to hit TDC.

The trigger angle also results in the maximum ignition angle.