Some ideas from the top of my head:
- You could add one space next to every open space, so it'd be a 3, 5, 5, 3 board instead of a 3, 3, 3, 3.
- You could add "day-night/reversal symbols" to the current open slots (or perhaps just two of them, although you lose symmetry) and whenever you step in one, the respective countdown goes down by one. In my mind it leads to more situations where you can account for cycles changing to make set-ups, or maybe it doesn't and breaks the current balance, lol.
- You could hard code it to 3 and 6 (or something) for the first turn.