title: Firebase Audience with time events criteria
body: <p>I would like to define an audience in Firebase based on last time an event was fired. For example, I would like to reengage users who did not open the app (event: <em>app_open</em>) last 30 days. </p>
  
  <p>I've been trying to define an audience based on this criteria with no success. </p>
  
  <p>Any help would be appreciated</p>