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 previous Toronto Master Gardener’s post, here, discusses how to go about pruning a very tall rubber plant (including branches), but the directions for pruning the central stem are applicable to your plant. Another very clear and informative description of how to prune for branching is available here: https://homeguides.sfgate.com/ficus-elastica-houseplant-grow-multiple-branches-72789.html