As much as I would like both ends to be done for both the statement of intent and to avoid the stadium looking lop-sided, I believe it will be done South Stand first, followed by North Stand when (not if) required.
My thinking is based on the same concept of how the Middle-East countries control oil supply to maintain price. I think some of that strategy will be seen here. I think with current waiting list numbers we can reasonably expect to sell 54,000 for all Premier League games and that is great news. What I can't see just yet, is our ability to do 60,000 for the likes of midweek games against Fulham, Stoke, Palace to name just a few.
And in a commercial world, half of the problem in convincing people/companies to buy corporate packages is the illusion that they are buying into something exclusive. Clearly then, huge amounts of unsold seats would not be great.
The 2 stage approach also allows for a new City Square and Club Shop (Hypermarket) to be constructed whilst both of those successful assets in their current location can continue to function.
In short, I won't be overly disappointed to hear it is just the South Stand first as I know the decision will be getting made for sound logistical reasons and that the eventual location of the Club Shop, Square and even Circle, will be the best available.
If success continues, CL qualification year on year, I suspect that the North Stand will be done by 2018/19. It's delay will also maintain the feeling of more good things to come by giving us something to look forward to!