Hi Baris -
When you're making any changes to the environment, whether that's a version upgrade, changing the configuration of the servers, or even just making form changes, it's always recommended to change as few elements at a time as possible. If something goes wrong during your migration/upgrade/reconfigure procedure, it will be harder to determine exactly what happened, and it will be much more work if you need to roll back or start over. Chi's recommendation of doing the Swing Box version upgrade first then reconfiguring to Advanced Availability means that you will have a good stopping point in between the operations - this is a good place to take backups and/or snapshots, in case it's necessary to roll back. While I'm sure it's technically possible to combine the Swing Box and configuration change processes, it's not something I would recommend doing - there's too many moving parts, so to speak, and it's generally better to take your time and make sure each part of the upgrade is done completely before moving on to other operations.