I'm a little confused: "I do take care not to overwater this plant." You mean your cutting? It isn't a plant yet, because it has zero roots. I haven't started jade from cuttings. But other things that I do start, the only thing that has worked for me is to dip the cut stem in rooting powder then stick it into well moistened potting soil, then put a humidity dome over it. (A two-liter soda bottle with the bottom cut off makes a good humidity dome.) The difficulty is to keep it alive until it puts out roots. So you never want the potting soil to dry out at all and you want to keep a humid environment around the leaves, so they don't lose too much water to transpiration before they can replace it through their roots.