At every stage:
Never spend months building systems without a playable loop.
This is for fun, there’s no such thing as a deliverable for this project. Creating is fun, savor it. Take joy in bringing something new into the world.
Looking back at all that has been accomplished is only possible if there is a log. Maintaining a dev log will help me not rush, as well.
Since AI is going to be a major part of the game, playtesting will likely be as unpredictable as actually playing the game for the first time.
Remember where I get resources, so credit can be given.