I understand your problem. Living in the woods, I place mine in my large driveway turn around and most of the time have to wait for enough satellites. I've waited as much as 15-17 minutes. With buildings you will/may run into the same problem. I go out in the open and before I am ready with the phone I have 7-9 satellites.
Well, the manual states 6 to get a set location. I like to wait to make sure I don't loose one just before take off.