Reply to Potty training...... when to start

We started potty training a few weeks ago and my son is 20 months. I highly recommend the Tiny Potty Training Book by Andrea Olson. We have completely stopped using diapers as soon as we started the program. My son is doing great! Only has an accident every now and then. In the book she explains that before the invention of disposable diapers in the 50s, children were potty trained by 12-18 months. In fact, most other places in the world have their children potty trained long before those of us in the US. I had a lot of people vehemently tell me that my son wasn’t ready, but it worked for us!