And continue for a few seconds after the healer is up, since they will rez with little health, or energy, or both.
Additionally, if a DPS has off heals, they also have a combat rez, and it should be they, NOT the other healer, that does the rez. It should be done immediately, and without being asked to do so.
EDIT: combat rez is also for boss fights only, not trash pulls.
If a DPS has a combat rezz, they should be priority over healers to use it, but they should NOT use it without being asked.
There are plenty of times you might not want to automatically burn your battle rezz (e.g. opportunity in near future to execute combat stealth + rezz).