what you probably should do is start with something stable and known to have a good reputation. I don't know where you live but the states we have a few potting soils that are pretty dependable. Foxfarm's ocean forest is an example. seems to have enough fert in it to last quite a while, but this amount of fert tends to cause the appearance of leaf tip yellowing or browning. as the plant grows, the discoloration tends to stop. sometimes it never happens, other times it does. depends on the plant strain and how sensitive it is to fert. I'd find a decent soil if I was you and trust it, water it then let it dry out before you water again. as plants grow they need more water so you would probably water more frequently. you can web search in your area for good potting soil.