You are setting the timing right if you set it at ~30% before top dead center. Newer electronic ignitions like RCExcel have auto advance which will advance the timing as the rpms increase. If you are using an older ignition like a C&H they may not have auto advance because they were meant to be used with an advance linkage, like original Brysons. To make sure you are actually firing the plug remove the plug and turn the engine over by hand and see if the plug sparks when the magnet goes over the sensor. If the plug sparks and you have fuel and air it should try to fire. I usually set my 5.8 carb at one and a half open on the high and one and a quarter on the low and tune from there. You may have to rebuild the carb with a kit and check the screen inside to see if it is clogged. Mostly the rubber diaphragm will lose it's resilience after setting dry for awhile.
Larry