Not sure if you found anything yet or if this helps, but I have an apartment in Berlin and am looking for sublettors and, or a housemate(s) just not quite as soon as you arrive. My house is in Mitte, near Prenzlauerberg and it is quite big (103 sq. meters) There are two bedrooms and a big living room. I have lived there as three people before and its really quite comfortable that way.
I have sublettors in there through mid July and have a conversation going about august with some SF artists, but they are not really clear yet about what they are doing,
I am a choreographer and bounce back and forth between Berlin and SF.