1. For all Freemium devices only one upgrade is permitted (whether it is APs or Switches). 2. The Switch/AP which is set to “latest software” or a specific software will get upgraded when the device reboots or when it restarts its activation process. If you do not want your device to upgrade automatically on reboot/restart of activation, you should set its version to “Do not upgrade” in the device catalog.
For a Device in Trial/Premium account, you can upgrade it using "Resource Manager" application, at any time.
Currently, we do not have a way to schedule an upgrade. That feature is coming soon.
Thanks, Venkat