Oh I am on similar situation now. I want to reschedule my IV interview that was slated for next month at the US consulate in Helsinki. But before my appointment date I can login and create a my profile online. However, since when I received the IL, I keep getting 'unable to process your request at the moment' whenever I Login. According to the instructions on the consulate website, I need to register my appointment before I can reschedule it. I emailed the consulate about scheduling my interview, and they replied that I need not to register my appointment. Now, I want to email them to request for reschedule. I will prefer to have the interview after August 2023, that will give me enough time to finalize my PhD in Finland. Please, do I need to mention my prefer month for the interview? Thank you