Why you should write now, and think about publishing later
Without fail, one of the first things writers bring up on their initial call with me is how they'd like to be published. This of course makes sense; you want to know where you're going to end a marathon before you start, after all.
There's a problem when you start to focus too much on that end goal, though; you chip away at the simple beauty of creation. You begin contemplating rejection by agents and publishers, then you're thinking about sales and statistics, and suddenly you're feeling the pressure of getting published before you even get a running start.
When you think too much about your publishing goals when you're still writing your book, you enter a headspace filled with logistics instead of ideas.
I'll give you the same advice I give my authors: Think about how you might share your story for a limited time (half an hour of research every now and then, for example), and then give yourself over to the writing completely. Enjoy the creative process, the quiet solitude of writing before needing to present yourself to the world as an author, the simple joy of bringing your story to life.
Because being informed about the publishing process doesn't necessarily mean that you're going to write a better first draft, but it might mean that your first draft never makes it to the page.