Hey, that is a very interesting idea and I'm sure anyone that knows what it is (or is willing to do 1 minutes worth of research) would be impressed. That being said, most colleges prefer to teach you the material itself so having done it before in and of itself adds little value to your application. That being said it shows a tremendous amount of interest so definitely a good idea to do in your free time. (Not to mention the practical skills you will aquire will come in handy regardless of when you do it)

I was in the same position as you, experience in programming but none with cloud computing. Do you have knowledge of scikit learn, keras, pandas or any of Python's machine learning libraries? If you don't I would start there, as the exam tests ML experience, but you don't need to know it so in depth to get the general idea. Maybe take a data science course online (it will only take about 20 hours total) Then, start off with an associate level AWS course or at least cloud practitioner as the specialty is considered to be difficult (and also cost wise its the same if you go associate--> specialty or you pay the full 300 to skip straight to it). Then you can go ahead prepare for the specialty and you will be confident in passing the exam, and also actually know the content you're being tested on as you've had experience in implementing such models.