Jonas Tyroller (a creator of "Islander") give us some time budget suggestion for the wowie jam. It helps to prevent this kind of problem. Personally, It was useful. I put it there :

Milestone Suggestions

You can use these rough milestone suggestions to make sure you stay on track if you want. Remember to keep it simple!

• After 5% of your time budget: You came up with multiple game ideas on paper and picked the most interesting one.
• After 25% of your time budget: You experimented with your idea a bit and the basic game loop is done.
• After 50% of your time budget: The most important visuals and sounds are implemented. Your game is fully playable.
• After 75% of your time budget: The game looks, sounds and plays even better. It might also have a short tutorial now.
• After 100% of your time budget: Final bugs are fixed,  game is uploaded to a decent looking itchio page.

Good luck, have fun. :)