Make a few two hands finger hangs of 10″-20″ only with your body weight, using the grip position that you feel the most comfortable with, choosing between an open crimp and a half crimp. Rest for 30″-60″ between repetitions, or more if you need to. The basic principle is to never reach muscle failure during the warm up. Usually, 6 to 12 repetitions should be enough, but you can do as many as you need, progressively decreasing the size of the edge you are using, starting on the biggest one and finishing on a 16 mm size. If you can hang for more than 10″ on 16 mm without effort, then make some additional repetitions on smaller edges, but remember, without reaching muscle failure.
Rest for 5′ before starting the test.