This is probably one of the hardest challenge among many moms. And you'll be surprise on how your kids will react to this thing.
I've been starting potty train for B since his first birthday. Some of my mommy-friends are even started since the kids are still little baby. But I do believe that potty train is something that you should teach your kid when they are ready, so we took our time.
I decided to begin as early as his first birthday just as an introduction, not for a full train. I didn't expect him to understand so fast either.