MBonk
With an ultimate I would start out with zero all around (tail, lower and upper wing).

Generally most bipes are positive stagger with no or minor sweep. For these planes upper wing incidence effects the stall and trim characteristics in the following manner. Positive incidence results in a nose downmoment with stall and negative incidence biases toward a pitch up in stall. I try to set the incidence to minimize trim change with speed. That's why I like to start with zero all around and adjust from there for aerobatic planes and not worry about stall unless it's ugly.