I just wanted to add my welcome and well-wishes for your wife and baby. You've received some great responses already...quite touching, I think.
To help answer your "unanswerable" question, the average timeframe from diagnosis to delivery is 2 weeks...remember that is an average. It does sound like your wife is in the right place and will have everything possible done to prolong her pregnancy and work toward a good outcome. I know you are caught up in the fears and uncertainty of this time (I would be too), but I am so glad that your wife's condition was caught early enough that this was even an option -that is a great blessing.
I agree with the previous posters -learn what you can, prepare yourselves wherever possible (I tend to live by the "prepare for the worst and be pleasantly suprised when it doesn't happen" idea), and do whatever you can to stay sane and help your wife do the same.
Please keep us updated, ask whatever questions you have, and feel free to vent your feelings here.
Sending my prayers,