Optionally, it should show up in the Boot Camp control panel. At least that way, you don't have to sit there with your finger on the option key.
Look for the silver/gray Boot Camp icon (looks like a square sitting on one corner in the lower right corner of the task bar), and right click it. Click "Boot Camp Control Panel."
You should see any bootable drives in the panel. Select the one you want to use, and click restart. Done!
In Windows on Mac, Boot Camp controls which disk to boot, not Windows. 😉