As Ron mentioned, you check for pinging while driving, with the engine fully warmed up. Typically at mid-range RPM's with the pedal all the way down is when the engine is most likely to ping (probably something to do with the advance curve of the dist not quite matching the engine's actual needs). If you have the timing set where you hear just an occasional ping under full throttle then it's pretty good. If you hear too much, retard it a little. If you *never* hear any pinging at all, you might think about advancing it a little. It's more of an iterative, ongoing process.

If you have it set so that it pings at idle then it is *way* to advanced. If it will even ping at idle - I'm not sure it will actually. Advancing the timing too far will kill the engine (it doesn't have enough momentum to overcome the early firing) and even if it were pinging, you might not hear it because so little air/fuel is being burnt.