Child care positions often require you to work weekends and evenings, especially nanny positions. Make sure you know your availability before you commit to a set schedule! If you have open availability, you can tell the interviewer, "Yes! I am happy to work whenever you need me!" If you have a few things on your schedule and you're not sure how this new job might affect those obligations, tell the interviewer, "I am flexible and happy to work when you need me, but I do have a few other weekly obligations. Which evenings and weekends do you need me? How often will you need me overnight?" It is much better to ask questions up front than to commit yourself and have to flake out later on down the line. Bring your updated calendar or day-planner with you to the interview to show that you are organized and reliable.