Also, It's currently about 4-4.5 feet tall. I have 8+ ceilings and would like it to grow to at least 6 feet with a heigh spreading canopy.

That you live in the US doesn't tell us much, and what you can/should/shouldn't do depends a lot on where you live. You might consider adding something like the info that appears with my user name, or at least a large city near you.

Now is the time to cut your plant back, but don't delay if you decide to do it. The plant will need some time to push new foliage before winter and the accompanying reduction in day length and photo-intensity arrives.

Cut the thickest stem longest, the stem that is the next thickest about 2/3-3/4 the ht of the tallest, and the thinnest stem about 2/3 of the ht of the middle stem. There should be less ht difference between the middle foliage pad and the top pad than between the middle and lower. After that, allow the plant to grow w/o any pruning until next Jun. At that time, you can prune off any branching that occurred on the lower stems below what you're developing as the main foliage pads.

Now is also a good time to repot into a soil that allows you to water to beyond saturation (so you're flushing the soil after it's completely saturated), w/o having to worry it will remain saturated too long, impeding root function or worse, causing root rot. Your soil plays an important role in the growth, vitality, and appearance of your plant. There is no sense in fighting a soil that works against you when with a little effort you can build (or in a few cases - buy) a soil that works for you.

Al

You added the second post while I was typing. If you want the end ht of the planting to be about 6', you should wait until the thickest trunk is just a few inches to a foot shy of that mark - the rest of what I said still follows and will be the best way to achieve your goal.

Al

Thanks for the reply. I live near sacramento, CA. It's 100 F here all this week, for example. The plant is in a relatively bright spot near a large window facing south.

I was worried about cutting it back because it seems like new leaves grow from the junction wear existing ones meet the main stem. So if I cut a stem back and there are no existing leaves below it then the stem will still put out growth? Because it seems like when I snap a leaf off it takes the little spiky shoot thing off with it.

I just transplanted to a larger pot and saturated with water... Using potting soil mix.

Did you repot or pot up? I imagine you potted up (different than repotting and not nearly as beneficial to the plant. The plant, repotted, probably would better have gone into a smaller pot and not larger. The plant much prefers to be grown on the dry side rather than having portions of the soil soggy. It's going to be a challenge to refrain from watering for LONG intervals if you cut the plant back AND potted up. With no foliage to drive the transpirational stream, the plant will use hardly any water until it flushes out again.

Al

It would backbud, even if you cut it down to the soil line.

Whatever you trim off can be used as cuttings to propagate more plants if you wish. Schefflera is pretty easy to root.