How Long Will the iOS 12 Update Take?
We don't know the exact size of iOS 12 just yet, but you can expect a fairly substantial download.
iOS 12 is a major update which means it could require a 1GB+ download. This means it'll likely take longer than your standard iOS release.
You can expect the download to take five minutes or less, but the installation process could take 10 minutes or more depending on your current version of iOS 11. Again, if you're running older software, your download could be bigger and your installation time could be longer.
Once you pull the iOS 12 update from Apple's servers, you might notice a prompt asking you to "Install" the software right now or "Later."
While most of you will probably want to install iOS 12 and get started, others might benefit from scheduling the installation.
If you choose to schedule the update can choose to install it while you're sleeping or you can have your device remind you to install it at a later date, sometime when you have time to monitor the process to ensure it goes smoothly.
If you do decide to install the iOS 12 update overnight, you'll need to plug the device into a power source.