Events in AWS with a deadline date can be rescheduled.
In the case of EC2, events can be rescheduled as follows:
Go to the EC2 Console (https://console.aws.amazon.com/ec2/) and select Events.
From the filter list, select the resource type as 'Instance'.
Select one or more instances, then choose Actions, and select Scheduled event.
Only events that display a deadline value in the Deadline column can be rescheduled. If any selected event does not have a deadline date, the Scheduled event option under Actions will be disabled.
Enter the desired date and time to reschedule the event in the New start time field. The new date and time must be before the Event deadline.
Select Save.
It may take 1–2 minutes for the updated event start time to be reflected in the console.
Limitations
Only events with a deadline can be rescheduled.
The schedule can only be changed before the Event Deadline.
Only events that have not yet started and are scheduled to run at least 5 minutes in the future can be rescheduled.
The new event start time must be within at least 60 minutes from the current time.