It takes about 1.25-1.5 mm of slot to get 1° of timing advance. You should be within around 1.5mm of the trailing edge of the plate to get 4-4.5° of advance.
That one side looks like it's dumping fuel. What's the history of the carbs? Known good? Float level right? Needle and seat clean and working properly?
I sold some pegs to OP. Smooth transaction. He didn't harass me about shipping it out or anything. Even offered to cover extra shipping costs I incurred sending it to Canukialand.