IOS 14.3 Update
My update on my IPhone downloaded and it's been stuck on "Preparing Update...." for awhile. How long should this take?
iPhone XS
Usually, 30 minutes would be more than adequate, but it depends on your network strength, data on your device, what is happening on your iPhone currently, bandwidth available, data traffic, etc.
Ensure that you have a good network (decent WiFi) and enough battery (more than 50%, keep it on the charger) and that your iPhone is idle...