I always rupture at 5-6 CP except in 2 places: on the opener (garrote-mut-rupture) and when I'm setting up for exsang. When exsang is coming up about 15 secs on cd I will use a 3ish cp rupture to get Rupture up over 24 seconds - mut to at least 5 cp - then I will pool energy To 90 or so, garrote at 2, vanish if possible, rupture, and cast exsang & kingsbane. This starts EP's 5 secs. In order to maximize it, mutilate to 5 or 6, wait til EP has .5 seconds left and cast envenom so it benefits from EP and refreshes it. Now you should have enough energy to get 2-3 mut's inside EP and refresh garrote without losing dmg.