The simple thing I do my case is:
mount /dev/a /mnt/fedora #this can be called 'mounting the top-level of the file system'
mount /dev/b /mnt/backup
btrfs subvolume snapshot -r home home.20200901
btrfs send home.20200901 | btrfs receive /mnt/backup #called 'bootstrap' or 'setup' with the first full backup
btrfs subvolume snapshot -r home home.20200904
btrfs subvolume snapshot -r home home.20200905
btrfs send -p home.20200901 home.20200904 | btrfs receive /mnt/backup #incremental
btrfs send -p home.20200904 home.20200905 | btrfs receive /mnt/backup #incremental
The thing that ensnares us all in Btrfsland is that it’s so flexible, and is not on rails, that it permits many different kinds of workflows and snapshot naming conventions. All valid.
It’s a good idea to just explain the simple case, and expect there will be many “but why?” questions. Folks will still love it and encourage them to experiment and answer their own questions.
A tiny “food for thought” at the end that doesn’t need to be deeply explained, two ways to restore: you can just copy individual files out of any of the snapshots on the backup. Or for disaster recovery you can do a full send/receive of the newest “home” snapshot to the new drive; the details of which could be a part 2 article.
Anyway I’m happy to answer questions and review.