10 weeks and 3 days, my son is laughing. I was talking to him and he was cooing back, a happy boy for sure. I kept saying Boo and the smile got bigger n bigger and finally a small giggle. Next day a gentle tickle to the ribs and I got a full laugh! Omg I'm so in love! I don't remember my 1st 2 babies laughing this early. Are your babies laughing yet?