How much should you breathe in before you breathe out?  When onboarding into a new job, as much as you can by day 30.

You can no more lead before you listen than you can breathe out before you breathe in.  Walking into a new role and giving directions on day one sends a powerful signal that you don't care what anyone else thinks, that you're not really open to listening to their point of view.  On the other hand, listening too much for too long runs the risk of positioning yourself as indecisive.

Get the imperative in place by day 30

We used to think there were diminishing returns to getting the imperative in place after day 30.  We were wrong.  There's a cliff.  After day 30, you're into the second monthly cycle of business.  People get re-stuck in their routines and think you're imperative is a lower priority.  So, generally, you want to listen through most of your first month, then gather your team and agree on the imperative.

Get a head start

The good news is that if you get a head start before the start, you can spend even more time listening (breathing in) before you launch your imperative near to day 30 (breathing out).

Listen through most of your first 30 days.  Then rally the team around the imperative.