PSA: If you have an Iphone 8plus (and probably 8) DO NOT upgrade your IOS to 10.12.3 if you plan to replace your phone. Apparently Apple released a version of the IOS that fixes a bug on this phone. But if you upgrade to it and try to restore your new phone from your last backup, it will fail as the version available on all other phones is one revision back. This is the first time in the history of Apple that I am aware of, that they have done this. The salesperson at the apple store said this is killing sales and Apple needs to fix this “immediately”.
On a related note, I am now running the IOS 13 public beta.