"I still have the iMac set up and running. I have not sent it in to Apple yet. (Trade in).
I have also have the mini up and running but nothing added to it yet."
If the Mini is up and running, you've created an account on it, right?
Is the account (as it sits now), "disposable"?
Nothing there of importance?
You need to realize that even if the new account has the same name and password as the one you used on the iMac, the Mini will see it as "a different account".
However, you could do this to fix that:
1. On the Mini, create a NEW administrative account. Give it a simple name/password (such as "temp/temp"). It's not really going to "hold anything". The IMPORTANT thing is that when you create it, it will occupy the "502" ID "space". The first account you created occupies the "501" space by default.
2. Now, log out of the first account (on the Mini) and log into the NEW "temp" account in the 502 space.
3. Now, DELETE the account that is in the "501" space. This "opens up" the space, and when you use Migration Assistant, your "old" account will "flow into" the empty 501 space.
Next... WHAT to migrate?
This is something you need to sit down and write out on paper.
On one side, enter the stuff that will go onto the new Mini.
On the other side, enter the stuff that will go to the external SSD.
Once you've got things figured out, connect your backup drive and the SSD so it's all there and ready to go.
I'd open up Migration Assistant next.
It will ask if you wish to migrate from another drive, so "point the way" to the cloned backup.
Give migration assistant a few minutes to "digest things".
It wlll "present you with a list" of stuff to migrate.
- Applications -- these will go to the Mini
- Account -- you need to be careful here (see below)
- Settings -- these should go to the Mini
- Data -- again, you need to be careful.
You want your basic account on the Mini.
BUT... if you had some really large libraries on the iMac (such as pictures, movies, music), THESE are the things you might consider putting onto the external SSD.
This is your choice, and thought and consideration are needed.
I believe that migration assistant allows you to go "inside" the account folder, and pick-and-choose which things (movies, music, pictures) you want to include in the migration.
You need to UNCHECK those things you DON'T WANT to be migrated.
If you have "other data" that resided outside of the home folder, you'll need to decide what to do with it, too.
Once you've got your choices made, click through and let migration assistant do its thing.
When done, log out of the "temp" account, and log into your main account (which should now occupy the "501 space".
Look around, try apps, etc.
Do things work as intended?
Now... with that done, turn your attention to the next step -- getting stuff onto the external SSD.
Again, having a CLONED BACKUP instead of time machine will make all the difference in the world here.
First thing... you need to take steps to prevent future permissions problems.
1. Click ONE TIME on the icon of the cloned backup to select it.
2. Bring up the get info box (command-i)
3. At the bottom, click the lock and enter the password for YOUR account on the new Mini.
4. Put a check into "ignore ownership on this volume" (sharing and permissions)
5. Close get info.
Now refer to that paper list you made up.
Locate and copy those items from the cloned backup to the SSD.
Do this "a little at a time".
When you finish with one thing (for example, your music library), open your music app and check things out for proper operation. Things ok? Then it's time to move on to pictures, etc.
When done, everything should fall "under the ownership" of your new account (because of the permissions trick above).
You thought this was gonna be easy.... right...?
(It's really not difficult... just tedious and time consuming...)