I have the EXACT same situation!!

I used another lines eligibility and I never had to wait for the phone to work cause I used the sim from the iphone 3G. All you will have to probably do is give the sim that came with the phone to the person who's line you used to activate. That person's became inactive today and had to put the new one in and activate on itunes since it's an iphone. What a nice thing that they are doing even though it was probably at&t who had the problem. One question, are you having any problems making calls and being able to use data at the same time?