My best friend did a trade on Swaptree.com and sent her book about 1 1/2 to 2 weeks ago but her book hasn't come yet. How long should she wait for the book before reporting that user?

We’re worried that the other person was just trying to get a free book without sending something. How long should we wait? Usually people only in the US use swaptree, but I’ve seen people from Alaska and Canada on there. For all we know it could be coming from Germany. So how long should we wait?