Since this is my first game jam, but I've been familiar with these for a while, I decided to not take any chances. The first day would be thinking about the idea and testing a few mechanics, the second day I had to have the whole game playable from start to end, and the third day would be just bug fixing, adjusting the difficulty or explanations to the player and polishing (sound effects, music, menu). It worked pretty well for me. I also decided to go with mechanics I'm familiar with, I'm pretty happy with the result.