Typical idle speeds usually sit between 500 RPM and 1000 RPM. In order to assist the idle control mechanism to achieve a steady engine speed, it is advisable to ensure that the ignition advance at the idle loads between 500 and 1000 RPM are similar, if not the same. It can be helpful to actually have the advance of the 500 RPM range to be slightly higher than the advance at 1000 RPM, so that as engine speed dips, the increase in ignition advance tries to raise the engine speed. This will help the engine to find a stable equilibrium.