When it will be about to be launched you will recognize it by the increased liquidity in the books of the exchanges. At that point you'll know that the launch is a matter of days.
If it launches the regulators will have to announce they have approved it first. Once the regulators either reject, or approve it they will announce their decision.
Does anyone whether this will be public information immediately? I mean, it really is quite simple to take advantage of such knowledge in advance in the Bitcoin market and I doubt there exist any laws against it.