I set the timing by looking at the piston through the exhaust port or the spark plug hole...You will find that a few degrees either way makes no difference...The dowel and degree wheel works well if you keep the dowel rod from moving...You can get a 10mm bolt at the hardware store...Screw it into the spark plug hole..Rotate the crank one way and mark the hub where the crank stops..Rotate it the other way and mark it again..TDC is exactly in between...you still need to know what number you want to use for full advance, and where the spark occurs relative to the sensor...Also do you want to use 28 or 30 degrees BTDC, or something else that someone says works better....Also how many degrees before TDC DA uses when setting up the igniton..Falkon is 2 degrees, C&H is 28 or 30, others may vary depending on the degrees of total advance the igntion is made for..
More trouble than its worth unless you just like to tinker...Read my post somewere near the beginning, it will tell you more about where it should be...The slots in the sensor won't let it go far enough either way to make much difference anyway...Best place is just past where it starts to show a slowdown in max rpm....Called "power timing" in the old days before we got all fancy with computers