With the new and exciting announcement forearming us with the features of Android L, it is fair to ask what this means for the OnePlus One owners who will need to rely on CyanogenMod to bring the OnePlus One to the party. So will there be a delay between the release of Android L and the availability of it to OnePlus One users? There will be a short delay, but the developers are used to doing this sort of thing and getting it out there quickly and especially considering they are working with the manufacturers. Of course the actual length of time depends on how much of a departure the Android L is from the current version. It is estimated, based on what little we do know, to take anywhere from a few weeks to a few months.
It is possible to see some less stable modifications come out early but for a stable and reliable version, it could take a couple of months or even a little longer, so it depends how much of a risk you would like to take when you go for the update. Ultimately only time will tell and at any rate, most people are more concerned about when they will get hold of the handset much more than they are in a hurry to update it. [source]