There's lots of general advice - read lots, study the basics of grammar, look at how-to-write books (with the understanding that the only absolutely indispensable and unbendable rule in writing is "clearly convey ideas to your readers" - that, and "a finished story is the only story that will ever sell") - but I'll address the last line:
Should I begin learning to write other books or start on the book now? Does anyone here identify with this?
I can relate to having ideas that seem too big for me. But one thing I've learned is this: you will never, in the history of ever, "ruin" a story by trying to write it.
You can burn out on an idea, certainly. You can decide it has a fatal flaw and "trunk" it, moving on to something else. You can realize that the story you thought you wanted to tell (Hero Bill's fight against galactic invaders, for instance) is actually something different (a scathing satire on superhero culture narrated by Hero Bill's sidekick and ex-lover.) But you will not ruin it - and will, in fact, likely learn more in trying than waiting around for that magical golden time to begin. Anything you write can be rewritten; that clock only runs out when it's published. Even then, if you hit it big, you can do one of those "author's preferred editions" or re-releases or some such.
If this book is the one burning a hole in your brain, at the very least do some brainstorming, to pin down your ideas now while they're fresh and hot from the oven of your brain. You can put the notes away for a while if you feel you aren't getting anywhere, or if you want to learn more about basic storycraft before wading deeper, but you'll at least have those notes to help get you back into that story, that world, that mindset when you do proceed. And even if you don't end up using those notes (see also the previous paragraph: anything you write now can be rewritten without tearing a hole in the space-time continuum, including brainstorming ideas and notes), it's good practice.
JMHO, of course...
