On your 300D the GPs will actually glow for about 40 seconds (or until you crank the starter). The light is just an indicator to let you know approximately how long you should wait. Next time, wait an extra 5 seconds after the light and see it it starts quicker.

Mine usually starts instantly when the light goes out (less than one crank). If the GPs are in good shape you might have something else wrong (valve adjustment, air leak in a fuel line, etc).