Day one: it starts in the afternoon at 7pm, so I plan on my whiteboard for a couple of hours
Day two: implementing a few concepts quick and dirty to check if its working like I think.
Day three: building the first prototype with an beginning and an end in mind. The game should work after the day is over. Not perfect, but anyone should get from begin to end.
Day Four: Girlfriend lets play and then bugfixing and gameplay mechanics. For example in the beginning I had a Button to respawn Robochan, my girlfriend told me it should be eigther on the hand or many buttons all over the place.
Day Five: Tutorial and Credits implementing.
Day Six: A Lot of bugfixing. A looooooooot :D
Day Seven: Nearly dying, because SteamVR stopped working. After that sending the exe to a friend an he played one way through. While he plays we are in Discord an he gives me Feedback and I setting up the itchio page. After that: publish.
Most important: spend at least 1hour a day for the game, because then you keep up the flow. At best: your first 4 hours of the day, because this is where you are most productive.