E.W.
I started potty training my son at the same age. It took about three months to get #1 down. Then another 5 months to get #2 down. He would not poop in the toilet. It got so bad he was constipated ALL the time. Then little by little he would poop during convienient times (morning or night, only in a pull-up when he had it on)
Then on his own he decided when he was ready to poop in the toilet. It was a very frusterating experience, but it's made me realize that they will do at their own pace. Eventually it will all be over, but when they are ready.