When did your baby start smiling and laughing?

DD didn't start until she was a couple months old, and even then it wasn't really consistent until she was about 5 or 6 months.

DS started smiling and even laughing the very first night he was born! He was laying on my chest a couple hours after birth, and he started laughing; the nurse said she'd never seen a baby laugh that early before! He's 7 weeks, and laying next to me right now laughing and giggling. Every time I gurgle to him or tickle under his chin he lights up and laughs; it's the cutest darn thing!