title: Best way to implement scheduled push notifications
body: <p>I'm currently developing an app that has some sort of user meetings system,
  recently the our product team requested to include some scheduled push notifications that will remind the users that they have a meeting 30 mins before, 10 mins before and 10 minutes into the meeting.
  (We use FCM as a push notification service)</p>
  
  <p>Currently for every new meeting we register a cron job on AWS CloudWatch Events rules, but I've come to realize that it's probably not the best way to implement it due to expected large number of registered meetings... (for example if we will have 100 active meetings, we will have 300 registered CloudWatch Events rules...</p>
  
  <p>So my question is there a better way to implement such a service?</p>
  
  <p>EDIT:
  The clients are both IOS(Swift) and Anrdoid(Java)</p>