The card will certainly take more a lot more than ten weeks to arrive. Make sure that when your wife arrives here, she gets an INS stamp in her passport saying that she has permanent status, and that she can go back and forth.

This stamp has an expiry date - be sure that hers doesn't expire for at least a year, just to be safe.

You can ask the INS agent - this is a minor detail and it is at the agent's discretion. You will have to make an appointment at your local field office for this, and stand in line. But it is worth it, because I guarantee you that her card ain't coming any time soon.