Earlier quoted context omitted.
I just did the Windows 10 upgrade on my laptop and at no point could I start the upgrade without explicitly clicking a button. In addition, the process starts by immediately rebooting (after downloading via Windows update and asking you to start it).
That's a really interesting story. Let me tell you another one. Both my wife's and my son's computers updated automatically, with no button presses on their parts, even after them pressing "do not update" on all the nag screens for the past several months.
On this laptop I actually had it download Windows 10 but I wasn't ready to upgrade so I held it off for another week. I still had to press something to get it to start.