Henry was 3 weeks old here. We started doing EC ("Elimination Communication" aka infant potty training or Diaper-Free Baby) when his circumcision cut healed. With our next baby, I want to start even earlier. It is so rewarding to catch his elimination, and helped us realize how much he was paying attention from early on.
In this photo, he was 4 months old. By then, we were catching almost all of his poops and many pees.
We practice EC when we are not at home as well. This was in Mendocino, when Henry was 9 months old. You see him watching his stream.
This is in Hawaii at 9 months. It was around 8 months that we started to consider him "potty trained," aka a graduate. We still have 2-5 pee misses per day, but he is definitely aware of his needs, which is our goal.