Whenever the carrier decides to send it out. There is lots of speculation, but no "Drop Dead, Confirmed" date. At least, none that can be confirmed and is believable OR has been released. All we have is nothing more than speculation.
I have AT&T and everyone one was swearing "By the end of January." It's February now. This happens with EVERY major update that is released. It will be here, when it gets here. Keep an eye on the forum. When it does hit the major carriers, there will be posts all over the forum announcing it. And then once they actually start the release, they won't release it to everyone that is their customers at one time. That would overload the servers. It will be over a 3-4 day process.
Simple answer.... relax...
Installing the software from Sammobile is not advised because if done incorrectly, it will void your warranty.