Selecting your turn to go last of all is the crucial skill in using the Governor.
If you select a little too late you could end up with fast enemy ships (Admonition) nipping in in the full knowledge of safely being able to activate on the chosen turn and get away before the Govenour's ship activates.
If you select a little too early you could find your ISD nicely in short range but unable to fire until the end.
I think speed control measures such as Konstantine, Q7s, G8 or even Ozzel could be useful in making the turn activations more effective. Ironically I think Price is better against other Imperials as they tend to come straight at you and so judging the approaches is easier. Flank firepower rebel ships can travel across your path and turn in or away from you to disrupt your timing.