Looks like the timing is a little too advanced. Look at the electrode strap. Notice where it changes color. Ideally that color change will occur right in the middle of the bend. If you do not have an illuminated magnifying glass you should get one as it is really hard to see the details with a naked eye. Peppering of the white portion indicates the onset of detonation. Tiny aluminum balls is detonation. Very hard to see without illumination and magnification.