Booting to Sony Vaio's BIOS

So the wife's Sony Vaio VPCSD has been running Windows 8.1 for a few years now and it's getting a bit long in the tooth. About time to upgrade to the latest and greatest Windows 10. I already have the installer on a USB stick. All I have to do now is to change the boot order to USB.

For the life of me, I can't remember how to get into the BIOS. Some quick Googling tells me to press the Assist button instead of the power button when booting up. Didn't help - went straight to Windows. What I noticed is that after restart, Windows 8.1 boots up very quickly. There's seemingly no time for you to press any of the function keys. I didn't even see any type of splash screen which would normally tell you which button to press to access the BIOS or the startup boot menu.

The Internet forums say to try holding F2 during bootup, or F8, or F11. I must've restarted the laptop more than 30 times, and using all of the function keys to no avail. Boot from DVD drive definitely works, but the Windows 10 won't fit on the standard 4.7GB DVD disk, so no point.

After hours of experimentation, I finally nailed it. Restart the laptop, then quickly press Esc. Once the Insyde H2O logo pops up, press F2 to access the BIOS setup pages.