Well the very first time I ever tried to book her, I emailed and started to arrange but then my circumstances changed. I had to cancel but I did it politely and I don't believe I got a response. At least I remember being worried she wouldn't agree to see me after that. But I tried a month later and she was her usual professional self and the comms was easily the best I've experienced from a WG.
Just explain your dilemma and she may understand. And tell her to contact me or password if she suddenly becomes available. If I got the cash I'll be happy to keep her busy.