I think you should , before kegging, pour 4 or 5 glasses of 1-2 ounces each of the beer and dose them as 4 or 5 different levels, taste until you find the one you like and scale up to the full amount. you could even do this after kegging and carbing, then you can tell what each level tastes like carbed. add the messured extract to each glass and top with beer to mix well.