I was much in the same position, I backed the coin on Kickstarter and then didn't even see the bit about the Adventure Spark until about a week before the deadline while I had two other deadlines for some short stories and dithered over whether or not to add to my stress and workload [while also taking up loads of time with 'real' money earning job]. Thus I could only really brainstorm and plan out the idea during work on Monday, and then write it up on Tuesday.
I loved the idea of Adventure Sparks, as a very creative and overambitious GM and storyteller I tend to struggle with prewritten modules and adventures because they feel too limiting/not permissive enough towards the GM to alter according to the moment or group or campaign. However I'm also a very huge scope/overambitious creator, so a lot of the work that went into mine was very much curbing my impulse to add more details, more features, more world building and so on. I also struggled with the line of keeping it vague enough to be system agnostic, but detailed enough to actually be an identifiable story and have its own character.
I've never really done game jams before, my other submissions were purely to show off some narrative fiction in a job application, so I'm unaware of the etiquette or social aspects involved in this sort of thing. Happy to learn through this though!
-Ian