Use the GUI settings panel to make CAPS LOCK an extra ctrl. Takes maybe 10 seconds.
Use same to make dock auto-hide. 10 seconds if I'm slow about it.
Install Homebrew. Maybe 15 seconds hands-on and a couple minutes in the background.
Use Homebrew to install spectacle. Less than 5 seconds hands-on time, done less than a minute later.
Start Spectacle and use its preferences panel to set it to start on boot. Maybe 15 seconds.
Remove all the pinned programs on the dock. 60-90 seconds.
The last one's the only part I've considered scripting, but since I only do it once every couple years at most, it's not really worth it.
Once I'm past a Mac's initial "welcome to Mac" flow and on the actual desktop, I'm only about 5 minutes (not all of it actively doing things) from having a comfortable environment set up and being all ready to install project-specific tools, as needed.
If I ever switch back to Linux (or FreeBSD, which is more likely at this point) I might go back to versioning and backing up a bunch of config and dot files. I need them, there.