If you're trying to make it perfect, you'll waste all of your time in tiny unimportant details (and you won't even manage to make something good). There are a lot of would-be writers with beautifully polished first chapters, and nothing else. Software is the same.

Likewise with making it good -- everything takes longer than estimated, and so life will likely intervene to stop you working before you even have anything working at all.

Lesson: get it working first (however badly), and evolve it from there.

Just do it, basically.