So "Tribunal" wouldn't begin until your character was level 9. That would kick off the Dark Brotherhood attack.

Daedric Quests in "Oblivion" coudn't not be accepted until you were a certain level.

What are the pre-requisites (if any) for Dawnguard to begin?

I just want the bare minimum please as I would like to avoide spoilers.

Thanks in advance.

Az

level 10

Thank you very much!

You need to be a level 10 until guards will tell you, but you can still start if you go to Riften and talk to any of the guards there. Look at the topic at the very top of the discussions page, the moderators say it all

ask guard

^actually sorry I lied, if you are under lvl 10 you can only pick up the quest by making your way to the Dawnguard Fort which is NE of Riften, no guards will tell you if you're under 10

Super.

No huge rush.

It will happen when it's time to happen.

You can go to fort dawnguard at any level, but you will only start hearing NPC's talk about it at level 10.

BTW dark brotherhood attacks in tribunal happened at level 1 too, at least for me it did.