sweetie they can call you anytime. Be ALERT
I have heard from a friend while your husband/wife is done with the interview just the next morning the sponser will be called and will be asked the same question. This way they find out if your both answering the question same. And not all questions will be asked about your marriage, dates etc....
Questions such as your husband/wife's fav color?
fav food?
tell the officer about your husband/wife for 10 mintutes. All his or her likes/dislikes, times they get upset.
etc....