We've found it really helps to talk about the fact that the first few days will be tough. She needs to settle, adjust to speaking English all the time, find her way around your home and get used to your ways - all before she starts taking on duties.
We always make it clear that our au pairs are welcome to be with us or in their room when they're not working and mean it. We ask what sort of food they'd like us to have in for them, especially lunches when they're usually by themselves. Make sure she knows how to get to key places, and not just places she needs to work. Bus / train station, local shops, town, cinema, college etc.
Finally, we always make sure new au pairs have a bit of time in the house alone in the first couple of days and encourage them to poke around, open doors, see if they can operate the oven, hob, dishwasher, washing machine and so on. It's always easier to do that when you aren't being watched. And if she offers to help when you're in the kitchen in the first day or so, emptying the dishwasher is great as it gives chance to find out where things go as you can keep up a running commentary!
Hope that helps. Good luck!