Or, you know, you could just wait till the Tank found it´s position before you regen him. That is what I was thinking much lately when doing my PLD Relic and WHMs dish out HoT´s even before i lobbed the first time
We are Tanks, we don´t fall by a few hits... sometimes, a flash dont hits everything, or im just lazy, or it ruins the fluid of the pull, ...
Just maybe wait until we are where we are supposed to be, CoS and Flash the whole pack and be good.
There is no exclusive right way to pull, as there is no exclusive right way to heal, for this... just different playstyles IMO
So be the smart one on the Team and adapt to it, as a good healer, you can handle both ;-)