I'd say you're ready, but just wondering, was your reference a model photo or another drawing (which is ok)? Because if its the latter, it's important to understand why the artist made their decisions of: lighting, hard vs soft edges, contour lines and lack thereof, line quality and weight, shape language, stylization, and altogether what to leave in or out of reality. I suspect this because these poses look familiar (or maybe I'm crazy). Also take straight forward photos of your drawings because the angle makes them look elongated sometimes. Also use brighter yet diffused light. (or just add a digital filter with higher contrast and brightness) Also maybe learn basic portraiture, at least the perspective and proportion of a Loomis head. Also remember that no one is ever truly done with fundamentals, and it's always great to revisit them. Best of luck!

You are ready! Very beautiful sketches. I am waiting for longer drawings :)

I started anatomy being far worse than you and still got a lot out of it. Go for it!

Your drawings are beautiful!! Sure you are ready! You will learn to see even better, because you will know how to name the things you see. You will also be able to start drawing from imagination. And then, you know, in life you never feel ready, but you have to start anyway, this is the wonderful adventurous side of life...

As ready as you'll ever be. I think there's a lot of hang-up on here sometimes about whether or not someone is 'ready' to start learning something. In my experience it's better to try and immerse yourself with different topics regularly, rather than trying to complete one fundamental at a time, if that's even possible. As far as anatomy goes, you should have a good conception of 3d space, basic perspective, and some understanding of figure drawing. All of which you seem to demonstrate above.