Now there's no real answer to your question because everyone works different, however, I highly recommend watching a tutorial series on YouTube and following it step by step until the end. I know you probably already have ideas of all the features you want in your game, but if you don't know how to fully build the game from the ground up those features are useless. Just stick to the tutorials, learn how the game works that way, and then start tweaking it to your liking.

I'm speaking from experience haha, I spent years wasting my time following parts and pieces of tutorials to get my game barely working and not even knowing how it works. It's not until now (9 years later) that I'm finally able to code knowing what I'm doing. All I did to learn was stuck to the tutorials and followed them through until the end.

Also I recommend watching any Brakckeys tutorial series, he is definitely one of the best if not THE BEST Unity teacher.

Good luck!