How do you know you are ready to start iterating? In some cases, very little is needed before the first iteration. In other cases, rushing to iterate (because you were told to) can lead to weeks of time wasted overly focused on delivering a poorly understood product.
In this presentation by David Hussman titled Getting Ready to Produce at Agile Mumbai 2010 Conference, David provides concrete tools for discovering your product context and assessing whether you are ready to start building and / or iterating. Participants learned tools for defining how much process you need and tools for truly understanding what you are building and why, as well as who will use it, why they will (or will not) use it and why.