Default Update Schedule
Oracle defines a default update schedule and this schedule is applied to all your instances.
If you don’t want to use the default schedule, you can select a different schedule manually.
1st Friday of a quarter (in the months of Feb, May, Aug, and Nov) - Test Preview instance
3rd Friday of a quarter (in the months of Feb, May, Aug, and Nov) - Prod instance
4th Friday of a quarter (in the months of Feb, May, Aug, and Nov) - remaining Test instances
Plan the timing of your Prod and remaining Test instances to ensure your update is like-for-like.
Allocate a sufficient amount of time to review and validate the new quarterly Update. We do not recommend continually shifting and pushing the Update out to the last available days since these days might be already fully booked by customers.