The incentive that Universal is giving its workers and contractors plays a huge role in how fast this will be built.
We've already seen what they can do, and we will continue to see this frenzied construction up until next year, when I'm almost more than sure it will grow in speed exponentially with increased ticket sales due to the opening of Transformers (which I strongly believe will open in 2013).
And once this takes off and we start seeing extensive infrastructural work with the facades and showbuildings, Universal will announce the plans of the expansion with a few pieces of concept art. The already stronger publicity team will take this head-on and will probably take a more conservative approach to what the Disney blog is doing (which is constantly releasing spoilers and alleged sneak peaks). They'll drive the expansion with strong secrecy, and ALL the forums will be bustling again, making us guess and speculate until we're at the millimeter level, but they'll give us what we want before too long, like with Phase I.
This buzz will lead us directly to an almost blatantly planned 2014 opening. Whether or not this happens will be a direct outcome of how successful the next few attractions before Phase II (and Cabana Bay) are to the parks.