In Adam Hartung's piece on Why Facebook beat MySpace, he describes how Facebook managed the whitespace by letting the market direct its actions, while MySpace's professional managers tried to direct the whitespace.

We keep learning how right Darwin is that survival of the fittest is about survival of those best able to adapt.  Fighting the market is like fighting the tide.  Sooner or later you lose.

Joining an organization with a wide-open, ever-adapting culture is like onboarding into whitespace.  Don't fight it.  Go with the flow.

Of course you should still follow the The New Leader's 100-Day Action Plan and get a head start, manage your message, and build your team.  But do this iteratively, continually adapting to new information and the ever-changing culture.

On the other hand, if the culture is not adaptable, then you need to help it learn how to adapt.