It really does grow like a weed. I got two cuttings about six weeks ago. One of them was green, the other more woody. The eBay seller said he had already had them in water a couple of weeks, so they should be ready to grow root within a week or so.
Standing in a glass of water on the kitchen windowsill (facing north), they were indeed rooted enough to plant them in perishable cutting pots after a couple of weeks, and the roots were showing through the pots within another two weeks. I potted them on into a 50/50 mixture of multipurpose compost and perlite at the weekend. They are growing at a fast rate, considering they only get eight hours of not-very-good light a day.