I finally upgraded my mid 2012 MacBook Pro Retina running a 1TB OWC SSD using a downloade DP7 installer.The upgrade went perfectly including automatic conversion to APFS retaining 3rd party trim enablement.But it took about 15 hours! I did this overnight, so the knucklebiting time was limited. Previous upgrades and installs on a MacPro were usually < 45min. But there was no APFS migration on that. I had to back up, wipe, reinstall, and restore.If it seems to take forever, let it trundle!Added: based on my router statistics, part of the update is a long and large download from a server as the first part of the update. This is with a full installer resident on the machine.

FYI: Long & successful upgrade on … | Apple Developer Forums

FYI: Long & successful upgrade on MacBook Pro

I finally upgraded my mid 2012 MacBook Pro Retina running a 1TB OWC SSD using a downloade DP7 installer.

The upgrade went perfectly including automatic conversion to APFS retaining 3rd party trim enablement.

But it took about 15 hours! I did this overnight, so the knucklebiting time was limited. Previous upgrades and installs on a MacPro were usually < 45min. But there was no APFS migration on that. I had to back up, wipe, reinstall, and restore.

If it seems to take forever, let it trundle!

Added: based on my router statistics, part of the update is a long and large download from a server as the first part of the update. This is with a full installer resident on the machine.