Congratulations! That's very exciting that your baby cutting is showing new growth. Your soil mixture sounds exciting too! If you're going to continue growing the plant in a container, I think you should stick with that same mixture, although I personally would leave out the vermiculite after the rooting stage. It retains moisture better than perlite does, and it's therefore a good ingredient when you're trying to root a cutting, but some of the existing vermiculite available to us has been contaminated with asbestos. In any case, it isn't that useful in a potting mix after your cutting has developed good roots.
I usually start cuttings in a 1-gallon container and gradually move the successful ones into 2-gallon, 3-gallon, and 5-gallon containers. After that, they usually go into the ground, mainly because I've discovered that I'm now too old to lift larger containers once they're full of soil and plants.
