To countdown or not to countdown?

[Greven]

Full party duty
Hard Savage/Extreme: Ready Check + Countdown (13-15 should be okay for everyone, it will probably change in ShB though).
Kick early puller.

Older Savage/Extreme: Countdown, grab boss if someone early pull and it doesn't mess up too much.

Easy/Unsynch: Pull away.

Main scenario: Why would you even Q this.

Light party duty
DF: Wait for buffs and sprint away!
If you can skip something do it, if someone get aggro grab the mobs.

Leveling: do a first pull to test the party.

Mentor: Just ask.

Alliance:
LOL.

But let's say the stars align and you don't find 20 headless chickens, and you don't feel like being one, a ready check before pulling bosses could do. It could suggest other tanks that you are going to MT (but no someone will suddenly wake up half in the fight deciding they are going to MT stealing the boss while adds roam free)

In any other case just go with the flow: if you die in a door to wall pull do smaller packs, if another tank insists on stealing enmity let him MT, etc.