I did early FP in Dallas, I showed them TSC letter asking to go to local office and infopass appointment, and told them the 800 number told me to do early FP so that it is done before my infopass appointement.
they did not really understand the whole thing, they realized I have a special situation and I dont think they wanted to really understand what it is. there were not many people then and they let me in. I think if there were a lot of people, they would have sent me back