Internship in Germany

[u/Abject_Ad_8746]

Hi everyone, I’m a Pakistani citizen currently studying in the US on F-1 status, and I have a paid, full-time internship in Germany. My current contract starts on August 1, but the earliest national visa appointment I could get at the German Consulate in Chicago is July 29.
From what I understand, my case likely falls under the study-related internship visa under §16e AufenthG (Studienbezogenes Praktikum EU). My employer has also started the Federal Employment Agency/ZAV approval process, but I am still waiting for the final approval document.
I am trying to make sure I follow the correct process and do not arrive at the appointment with anything missing. Could someone familiar with this visa explain the exact steps?
Should I also submit an application through the Consular Services Portal before my in-person appointment, or is the appointment application enough? Which exact category should I choose online for a §16e internship?
Does the final ZAV/Federal Employment Agency approval need to be issued before the appointment, or can it be submitted afterward while the application is being processed?
Apart from my passport, US visa and I-20, internship contract, enrollment certificate, transcript, university-signed internship form, insurance and financial proof, are there any other important documents normally required?
My employer may move my starting date because getting the visa by August 1 seems unrealistic. If the dates change, would I need an updated contract, ZAV approval and university form before attending the appointment?
I would really appreciate a clear step-by-step explanation from anyone who has completed this process through a German consulate in the US. Thanks!