When did you feel comfortable leaving your baby with someone else?

When was the first time you had a sitter (including a family member) for your baby?? My baby is 9 weeks old and my in laws are getting so mad at me because I won't let them babysit. Am I being crazy?? Like that is sooo young I feel.. I don't want to leave him yet and they are making me feel like crap because of it... When was the first time you left your baby?