每日吃瓜

Hi, I have a Portulacaria afra tree and I was told to get a liquid bonsai fertilizer. It's Dyna Grow, I think it is NPK 7:9:5 and I'm wondering how often I have to fertilize the tree, some people say every two weeks, and others say once a month. I am also wondering how often I should water it, so far I have been using a moisture meter to judge, when the soil is kind of dry I water the tree. I just want to know if I am doing this correctly.
Thanks in advance.