Welcome to the Wefugees community and thank your for sharing your question with us!
How long has it been since the personal interview? Am I understanding it correctly - you already received a letter from the court stating a positive decision has been made?
I've had a look and found a website that explains the steps of applying for asylum, and in this section the process after the personal interview, pretty well: http://www.bamf.de/EN/Fluechtlingsschutz/AblaufAsylv/Entscheidung/entscheidung-node.html
It seems impossible to say how long it will take until you receive the BAMF answer by post, but most sources state that it can take a while and is extremely important that you keep track of it! For example, check if the letter has been handed to a neighbor, a shop, or a post office/ post center etc. (If the answer was negative, the time period to make an appeal is very short).
I hope this helps to answer parts of your question. Please do let us know if you need further assistance!
All the best,