Don't bother releasing all three at once. Just release two kill them, then if necessary release the third and kill it. I'd recommend releasing Time Warden and Nether Scion first since they will reduce raid damage by the most (by making Fireball Barage avoidable) and making the boss miss frequently on the tank. Both drakes should be on the other tank. Both combined will hit harder than Halfus alone, but Halfus does hit harder than either of them. Hunter can misdirect the Nether Scion over to the paladin tank who picks up Time Warden right from the start. Once the second of the two drakes is approaching death, then release the Whelps (don't release them as soon as the first dies).
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.