ingles2, it is a nailbiting thing. I use the questionnaire to screen applicants because I get literally hundreds of responses. I think that is because I live in London, not for any other reason. They just see London and don't bother to read my requirements, so indicate interest even though the start date on their profile, say, is completely out. I don't contact those.
Only those whose profile are in line and which I like I send the questionnaire to, say, about 5-10 candidates. I will be lucky if half reply, usually not at once.
Have you had more interest to your ad? The alternative is to send an email giving them more details about yourself, eg link to webpage and ask if they are still interested. If they reply, you can then pick up the phone and get their responses by phone to a shortened version of your questionnaire. Of course, this presupposes their standard of conversational English is quite high- which is a very good thing to have esp if you want to be able to instruct your aupair over the phone.
It is more timeconsuming and costly but you get to where you need quickly.
When do you want your aupair to start?