Sounds similar to my experience with her a few years ago. Had at least a few hours notice - may even have been days - but wasn't ready and I spend half an hour sitting around in her flat waiting for her. At least she did let me in to wait, but I had only booked 30 minutes anyway because I was short on time - so being delayed 30 minutes wasn't good.
That said, she was proper enthusiastic once she was ready!