Interviews take place at the agency but is a home viewing possible?
Interviews happen at the agency on a schedule basis. It allows you to interview multiple applicants during the same session.
When you find someone you intend to hire, you are welcome to make an offer to her directly and to agree together on the employment conditions. This is the best way to secure the employment of a helper, especially if multiple families want to interview her.
Alternatively, if you are interested in hiring her but you are not ready to make an offer yet, you can invite her for a home viewing so she would have a better idea of her work environment, and you would have more time to make your offer. It is also a good opportunity to get to know each other better and the expectations you have.