With how of anticipation does a military gets orders to change location?

I have a friend who's in the military. She and her husband are GI's and currently stationed at Aviano AB in Italy. She just told me that she received orders with her hubby to get back to the U.S. but didn't told where exactly and when is that going to happen. I've asked her but no reply received what so ever. Is there a way of having an idea how long she might be staying in Italy or is that she doesn't know herself yet, even their new base?