Just make small changes and see what happens.
Repeat the same sort of small changes and checks and learn what your setup likes.
No one has a broad enough experience base on your engine to diagnose your next step better than you can. You obviously under stand the basic elements of testing and then making an adjustment, then seeing what happens.
As a general rule WI is most useful when you reach knock limited performance levels. You now know about where your setup crosses that threshold. For most setups, you would then dial in settings of fuel/air and timing that are just a bit over the edge but turn on the WI.
If you now have no knock, then you need to find your best timing for the WI. In your shoes I would probably add a bit of timing in small steps.
You don't want to run more timing than necessary to get about 99% of max power. Beyond that point cylinder pressures (loads on bearings) and such go ballistic with very small additional changes. In studies on WWII combat aircraft studies they found the timing that produced max power than pulled back the timing until they saw a 1% power loss --- this is what they considered MBT (Minimum best torque) timing.
If you see no significant change in power as you add timing you have probabably gone too far and need to back up in very small timing steps.
When you get to that point back off the timing just a bit, then start leaning things out.
After you have made noticable fuel changes you will probably want to re-check your timing is still near MBT. When you get to the point your seeing no increase or rapidly slowing improvements in power, as you lean things out, you are near the best fuel / air ratio.
At that point I'd add a bit more water/alcohol and then start the step wise process over.
Just a guess as I'm using my psychic powers here
Larry