It is actually getting too tall unless you want a taller plant. It needs a bit more light. It still needs to grow more and develop the trunk and branch structure before it is ready for shaping. So, right now I would put the plant in higher light if possible and let it grow out more. I might cut or pinch back the tips and pinch the top to keep it from getting taller. Bonsai, the character and movement of the trunk and branches are much more important than the leaves. You want the tree to be a miniature of nature. The natural tree will faces many obstacles and stresses in life and one of the objects in bonsai is to "age" the tree. Show the effects of wind, erosion, and time on the bark. That is what the windswept and lightening strike bonsai styles do. Growing in or over a rock, exposing the upper roots over time and showing the gnarly branches and trunk through the layers of leaves. by regular pruning and root confinement the leaves of the bonsai will get smaller. The leaves should be in scale with the ultimate size of the tree. It will take more than 8 months to do this. You can start thinking about a style and guide how you want the tree to grow. In a formal upright you would encourage more lateral branching and a pyrimidal shape. You also want to do the front left, right , back training of the branches you want to keep.
I am not skilled enough to try to train a starter plant into a style that I want to do. Instead, I let the plant grow and just keep it small and branching and hopefully growing evenly 360 degrees. I will take a long look at the plant and I might start out in one direction, but I will break something off. I just broke off the top of my pre jade plant and my Jaboticaba fell over too long and the main branch has a squiggle now. These accidents will make me have to rethink where I go from here, but it is all part of the process. Sometimes plans have to change and older plants also have to be redesigned if they get disease or get to be too large. In the end, the plant will tell me what I should do. Training usually takes place slowly over a period of years. Mall sai are different. The emphasis on mall sai is to get a small tree with usually "S" shaped branches for interest. It is not bad if the person who buys the plant really likes it.
My pre-bougainvillea bonsai does have a crossing branch, which is usually a no-no for good design. However, I find it less unappealing than an obviously big scar which will look cut off and not natural. Cutting off that branch would also mean essentially cutting the tree in half. I could make a separate bonsai from the part if I cut it off. However, I like the way the tree overall looks now. The bonsai master told me, I am growing this tree not for selling or to be "perfect" bonsai according to the rules. In the end if I like the way it looks, then that is o.k.
In the end, you will have to make choices and sometimes you will also make mistakes. Think of them as opportunities. In the end what does matter is if you are happy with the result.
Happy gardening in Hawaii. Gardens are where people grow.