I cast my Adlo as soon as i see the plummet animation, which is easily noticable by twin rising up. My adlo will go off right after the plummet and be ready for the DS that comes after it. If you do adlo too early, the plummet will take it right off and you will have to cast it again.
There is this beautiful spot where you can cast a physik and it will hit the tank after the DS, and not be affected by infirmity. I focus target twin, and i start casting physik when Twin's cast bar reaches the 'D' of death sentence. I almost never have to use my lustrates (unless the DS happens to do a massive amount of damage still, I only need to use it once). And the rest of my aetherflows i save for cleric stance>energy drain on conflags.