If it all goes as we expect it to go (nothing at Blizzcon, Nostalrius reopens), I think that it's going to be a little more than three days.
The Nostalrius team will probably make the final decision after Blizzcon (as opposed to it having been made already and kept private), which means that they won't have their hardware and software in place right away. Setting up this whole thing takes time, not to mention figuring out every last detail and being sure about it in order to hit the start button (remember, there's a lot at stake).
My estimation for all that is a month minimum... But at least we'll know

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