I suspect that what may have happened was the initial date was established shortly after acquisition of the land closed, and was based on what at the time seemed to be reasonable planning assumptions for the time required to obtain the necessary approvals and construct the building. I think it is obvious that things did not go as planned - obtaining planning approval for the configuration and density of the building being sought, iterations of architectural revision, the extent of contamination in the ground, and the late acquisition of the south west corner portion of the lot (its prior owner had been holding out, but passed away during the approval process enabling its acquisition) all served to stretch out the project.
Once the delays started building up, I am sure Pemberton realized the original dates were no longer workable. Not wanting to have an ongoing sequence of new target dates, Pemberton waited until enough of the project uncertainties had been resolved, to provide a new date with which they felt more comfortable. Now that design is finalized, all its approvals and permits are in place, and the excavation and below grade construction has reached the point where the contamination issues have been contained, from here on it is much more of a standard project process, most of the uncertainties are gone, and the revised date has been released.
