In an interview with Howard Stern on Hey Now Howard Stern Podcast, Big Bang Theory star Mayim Bialik said, “Babies are born giving signals when they pee and poop and if you learn those signals and reinforce them they will get them stronger and more clear. We taught our kids to sign. By the time they were 12 months old, they were signing for potty. They couldn’t walk, talk, or eat solids — but they could sign for potty.”

Source: https://www.buzzfeed.com/kristatorres/bekah-from-the-bachelor-infant-son-potty-trained