So, let's say 'Dave' subscribes to your Event Calendar (because he loves your events obviously). How long does it take for whatever calendar is used to subscribe to show your new events.
My attempt at a simple answer: Up to a few hours...but it depends.
Unfortunately there's no simple answer to this as it depends on many factors, but I'll walk you through it.
Our side (Event Calendar App)
We do a thing called 'caching' in the background to make sure your events are delivered super fast. Therefore we constantly update the world to any new events you have every 75 minutes. You could get lucky and post the event just before the refresh, but worst case scenario it's 75 minutes.
Their Side (Whichever calendar app they choose to use)
The next part depends on which application they used to subscribe to your calendar. Every application 'checks' for updates at different time intervals:
Claims every '12 hours' https://support.google.com/calendar/answer/37100?hl=en&ref_topic=1672445
They don't seem to state a time, but from testing it is variable from 1-3 hours.
They also don't seem to state a time, but from testing it is variable from 1-3 hours.
Yes another app that does not specifically state a time, but does seem to check every few hours.