Decide How to Download iOS 10.3.3
When it comes to how you download iOS 10.3.3 on your device, you'll have a few options.
If you plan on installing the iOS 10 update Over-the-Air (OTA) through your device's Settings, you'll need to have at least 50% charge.
If you want to avoid installing via iTunes, now would be a good time to find a Lightning Cable and charge up your phone or tablet.
If you do decide to install Over-the-Air, and you want to get it downloaded and installed ASAP, you'll want to find a fast Wi-Fi connection.
Again, if you're coming from something old like iOS 10.2.1, your iOS 10.3.3 download will take awhile thanks to iOS 10.3 and the changes from iOS 10.3.1 and iOS 10.3.2.