Start desktop from the command line

What is the problem?
I installed the desktop environment in OctoPi, but did not select "start on boot". I only want to run it occasionally. I just don't know what command to use to start it!

What did you already try to solve it?
Tried: startx, a bunch of other commands Google came up with.

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)

OctoPi (today's version, just installed), Pi 3+.

sudo startx should start the Raspbian Desktop if you've booted to a console.

This doesn't work for me

Let's keep this to one thread, okay?

Unfortunately, it doesn't. Have tried via SSH and keyboard directly attached.

Any other ideas how one might start the GUI after it is installed?

Let's keep this to one thread, okay?