The factory CG range goes from Extremely nose heavy to really nose heavy to nose heavy. Many people find joy at around 160-165mm from the LE at the root, but there are others who have gone up to 190-195mm and report everything is peachy. Start towards the rear of the factory range - it is not a "rearward CG".
iron eagel is bang on with how it is measured - always at the root where it meets the fuselage.