Update to 12.0.1 first
If you're one of the lucky folk who have just got one of the brand new MacBook Pro M1 Pro or M1 Max models, it has almost certainly come with macOS 12.0 build 21A344 pre installed, and the first thing you want to do is to update that to the release version of 12.0.1 (once it has been released). That includes some important fixes which will make life simpler, and is worth doing before you attempt any migration from another Mac or backup.
- Personalise and set up your primary admin user account with the same username and password as the older Mac you intend to migrate from.
- During personalisation, when you’re invited to migrate, don’t.
- On completion of personalisation and setup, install all macOS updates.
- When you’re then ready to migrate, connect old and new Macs using the fastest method available, such as Thunderbolt.
- Open Migration Assistant on each Mac.
- Set Migration Assistant on your new Mac to receive the migration, and that on the old Mac to be the source.
- When you’re asked whether to create a new user or replace the existing user, select to replace the primary admin user.
- On completion, make any adjustments to settings, etc., and ensure that it’s properly connected to iCloud.
- Make the first backup from your new Mac.
This was particularly important last year with the first M1 models. Hopefully the fixes in 12.0.1 won’t prove as crucial as those in 11.0.1 were.