If you have a OnePlus One, you should expect to be prompted to download the CM12 OTA any time now. Check out the CyanogenMod blog post. Alternatively, you can directly get the OTA ZIP cm-12.0-YNG1TAS0YL-bacon-signed.zip. You’d need to flash the OTA ZIP manually if you’re coming from the CM12 nightlies, or have some other ROM other than the official CM11S that came preloaded on the OnePlus One.
Flashing the OTA ZIP manually is pretty standard stuff. If you’re not familiar with the process, just check out the OnePlus forums, such as on this thread. There’s a bunch of alternate links to get the OTA ZIP too, in case the CyanogenMod download site is overwhelmed.
The official CM12S is not quite the exact same thing as the CM12 nightlies that I imagined it should, apart from the Google Apps that cannot be included. For example, the Cyanogen Themes aren’t quite the same. CM12S default theme is pretty nice, except for the default flat icons. That, fortunately, can be easily changed though the Cyanogen Theme. Just mix-and-match what fancies you. I particularly love the translucent lock screen in the default theme.
CM12S is really sweet. It feels like my OnePlus One is a new phone all over again. Have fun.