You normally use wood that is somewhere between green wood and brown wood. Normally cuttings are started in the late spring/early summer but I would be tempted to try it now if you have one that you really want to propagate. Try getting one node with two sets of leaves. If the leaves are really large, try trimming them back somewhat to reduce water loss. Cut a divot or slice out of the bottom portion of the stem and dust it with rooting hormone and place it in a container of premoistened sand or rooting medium of your choice. You might have luck with either tenting the pot with a plastic bag or even enclosing the pot in a mostly closed ziplock bag to increase the humidity level--just make sure the plant doesn't get too hot either way. If the plant roots, then you need to make sure that the plant gets enough light over the winter or you could end up with a leggy plant that is prone to getting aphids or similar pests.