Where does the writer's journey start?
If you want to become a writer, you need to know the first step: GENERATE TEXT
Where to start? AT THE BEGINNING...
To take writing seriously, the writer must know what it is that he wants to accomplish. Fiction and nonfiction are worlds apart in execution. What fits your aspirations, talents, or goals? After choosing which path you want to walk, you can more easily answer subsequent questions. Whether to self-publish or traditional publish is a topic that needs researching from your perspective. Again, these approaches are worlds apart and will require different things from you as a writer.
When I started writing seriously, I knew I wanted to write fiction. Research told me that the most popular fiction genre was romance. That was a comfortable fit for me, so that's the path I chose. Being self-taught, everything took a little more time and a lot more effort, but if work doesn't scare you, it's all doable.
To sum it up. Start at the beginning. What is it that you really, really, want to write? When you've answered that, you can then begin to map out your Writer's Journey.