I think for the sake of managing expectations, people should at least consider that the festival might not happen in chapter 5. The setup for the flower king dark world, the dark world itself, and whatever fallout it has, could take place in the morning before the festival and be plenty of content to fill a chapter. All of the foreshadowing for chapter 5 relates to the flower king and not the festival, too.

I actually think this could be likely since chapter 6 seems to be a big turning point before the author is "swallowed up" by his creation in chapter 7. It would make for a great set piece to have the entire town gathered together for whatever crazy shit is going to go down.