I’ve propagated a rubber tree cutting from a plant at work. It has finally sprung quite to life and is opening up many new leaves. It is about a foot tall. I am wondering at what point I should cut it in order for it to grow multiple branches, or if I need to do that at all? It is a singular stem at the moment.
Congratulations on growing a rubber tree from a cutting! Rubber trees can be pruned to induce branching. In your case, you may wish to give your plant a little longer, until it reaches the height you want, as one of the ways to induce branching is to prune the central stem, or leader, of the plant. A very clear and informative description of how to prune for branching is available here: How to Get a Ficus Elastica to Grow Multiple Branches