If you didn't elect to turn on iCloud backup when you upgraded to iOS 5 or set up your new iOS 5 device, you can enable it through the Settings app on your iOS device, or by connecting your device to iTunes and choosing Back Up To iCloud from the Summary pane. The initial iCloud Backup takes a few minutes, depending on how much data needs to be uploaded. For example, if you have several videos in your camera roll, the amount of time it takes to perform the first backup will be longer. Subsequent backups can take mere seconds to a few minutes, as, like Time Machine backups, iCloud will only back up what has changed on your device.
iCloud Backup will automatically back up your device once a day, according to Apple's website, and in our experience, it doesn't back up every time you are in the presence of Wi-Fi and plug in your iOS device. However, when it is performing a backup, there's no indicator on your iOS device. There's also currently no way to schedule an iCloud Backup.
Roman Loyola is a senior editor at Macworld