Anywhere, from 5-12 before top dead center is a good starting point. Run as much advance as you can with out hearing any pinging. FYI: advancing the timing is going further up the scale on the before top dead center, e.g. 12 BTDC is more advanced than 5 BTDC. The more advance you have the more low end pep you get, of course till your engine starts pinging, which is bad.