You could indeed think of it as starting on the root of the dominant chord you're substituting. So you would start on G, not A in your example.My teacher taught this lick starting on the root. So it is the root, flat seventh, flat fifth, and third. Are you saying it should be considered as the ninth, root, flat sixth, flat fifth?
So playing in the key of G, would one start on the G or the A? If you consider that it starts on the root, then one can start the lick on the sixth, tritone, or minor third of whatever key you're in.