Our LO's have slept with the white noise machine (on the heartbeat sound) since they were about 5 weeks old. I'm never sure if it does anything...I can turn it off and they seem to sleep just fine, but it's so ingrained in our routine that I'm scared to turn it off before they're asleep. That said, I don't want to sleep with a fake heartbeat on the baby monitor for the rest of their lives.
When did everyone nix the white noise? Was it any big deal?