According to some quick Googling, written installments happen after movable type's invention, which makes sense. Before that, was anything done in installments? For example, did anyone perform the equivalent of the modern sitcom on a stage? Thanks in advance for any insight.
I can't speak to it being the earliest but my mind immediately jumped to the 10th century Maqamat of Hamadani as being an example of "episodic" fiction in Arabic. The basic setup involves the narrator, Isa ibn Hisham, travelling to a new city or entering a new place, encountering some situation where he encounters a man who is inevitably revealed to be the rogueish and clever but friendly Abul Fath al Iskanderi.
You can read read translations of the surviving stories here: http://www.sacred-texts.com/isl/mhm/index.htm