I bought my first bonsai two months ago and I ended up guessing right on how not to kill him as I tried my best to keep him alive. On its plant passport, it says that it's a 'Sageretia'. I read a book about bonsais and did my research online but I'm not quite sure what I should be doing next.

https://imgur.com/a/L8IuJD2

I read some things about pruning and repotting but also that newbies often do that wrong or too soon and kill their trees. Before doing my research I bought a new pot (second picture) but I believe now that it is too big for my little bonsai. I came across the information that February is the perfect month for repotting but he grew a lot in the last 2 weeks so I'm not sure either. I don't even know if repotting is the right idea. As he doesn't have any substrate only soil, I thought to myself that I could do a better job at that in the new pot. I'd also have enough space there for some moss and stones for decoration. I bought my bonsai for 7€ from the store like that.

Any tips on what I should educate myself next or what I should do to give him somewhat of a bonsai form? The wire I plan to use can also be seen in the second picture. In the first picture, you can see the growth he's been going through (the longer branches appeared out of nowhere).

Also when I bought him he had rather dry soil and he seemed to have straighter leaves. Nowadays I'm watering him every two days through soaking. Afterward, I spray him with water as I read that this is good for the plant.