If I follow foxfan correctly he is saying something like this.
You want 15* of advance with the SPOUT out. So you set the dial or the LCD on your timing light to 15*. Then you mark the 0* mark on the balancer so you can see it when the light flashes. Then all that you need to do is pull the trigger and adjust the dizzy so that the pointer lines up with 0* mark. If you want 13* you just set the dial or LCD to 13* and adjust the dizzy until the pointer lines up at 0*. And pretty much repeat if you want to change your timing. This way you don't end up with a bunch of different marks on your balancer.
Me, I'm to cheap to go buy another timing light and just work with the one that I have had for the past 15 years.