I started watching Baby Signing Time! DVDs when my daughter was four months old. I'd learn the songs and signs from the videos and then sing and sign them for her. I liked it so much, I made American Sign Language songs (like Apples & Bananas and Baby Needs a Diaper Change) a regular part of Infant Story Times at the Burien Library.
Research shows teaching your baby to sign may reduce frustration and tears by improving communication. For example, some babies can use signs to ask for what they want instead of crying.
If you're interested in learning more about sign language, here are more resources:
Baby Signing Time Preview: