Ok, let's all take a deep breath. From last year's thread, it seems like they call by batches - each batch consists of those who interviewed on the same day and everyone accepted in that batch can expect a call within 24-48 hours of each other. From the comments of our lucky SDN peers, they have begun calling those accepted from the first two interview days (9/14 and 9/16). So unless you interviewed on that day, there is no cause to panic yet. And even if you did interview then, it's been maybe two hours since calls have begun (for many, many people) and at the end of the day, the amount of stress we experience will not alter the decision we received.
So. Good luck to all of you, I'm there with you. BUT, take solidarity with me in closing SDN and Reddit, taking a walk/getting a snack/going on a run and forgetting about this damn uncertainty because the call will come when it comes.