This post in reference where to locate your CG. Do a Goggle Search for (MAC+rc models), read the information provided. It has been my experience that the manufactures reccomended CG is very conservative. Normally between 22-27 percent of MAC. This is fine for your first test flight but not flying acrobatics.
The longer I stay in this hobby it astounds me to see the lack of aerodynamic knowledge. I once assisted what I though was an experienced modeler prep his new 1/3 scale Cap for its' maiden flight. Ever thing on the plane was perfect from engine run-up to range checking the radio. All set and ready to go he proceeded his takeoff run. Upon rotating the tail went down and the model rocketed almost vertical skyward. His excellent flying skills saved his airplane from disaster and upon landing that inevideable question arose. Did you balance the Cap per the plans? His answer was yes. Well, it comes to find out the plans were wrong and if was not for his skills the plane would have been history.