I'm going into my third year in the hobby, but year two was completely left to just let things grow and work on my actual home garden for my new home. Year one was me asking questions I could have probably found on the forum, and being about as psychotic of a nursery and big box hunter as the rest are when they start. I killed one large spruce, a nice procumbens specimen, and a small baby mugo. RIP.
Since I don't have one single tree in a proper bonsai pot to this day (except for a specimen I bought at natures way), what I've found to work for my not so OCD, but getting there, watering habits is just a nice organic potting soil with barky bits that I amend with additiinal small pine chips. I know what I do is probably frowned upon and do want to get I to the weeds about soil chemistry this year, but I've done what many recommended early on, which is to learn to keep trees alive, learn about their specific needs, be patient, and don't chop every tree up into what you want your final tree to look like when you get it out of the car.
That said, if it were me, I'd get two of the same pieces of nursery stock, amend them with an organic potting mix and the other with akadama/pumice, and see how both fare for you entering next season or more. Might be a fun experiment, and I'm sure you'd glean quite a lot from it. Would be a fun thread to watch, perhaps. Good luck.
Chris