There are 24 teeth on the wheel, as I remember. Setting one tooth off means 15 deg off.
You still can have the same idle performance, but you have to adjust everything off 15 deg to get the correct idle. And in that case, the idle adjust screw looks very weird, because it is too long(or short, I forget) .
I did compare this before, run with 1 tooth off for a whole month, all the timing set is correct, but only except for the idle screw.
Setting 1 tooth back to normal, every adjust looks normal too.
My specific way on my model, 1977 1150 is. Align the wheel, pulley and 3 dots to a line. There is a bump dot on the edge of pulley to match with the bump dot on the powerhead, matching them means you have 1 tooth off. Turn the pulley clockwise 1 tooth. This only works for me, I don't know other models.