With both of our it took 9 months for each of them to be trained, but not reliable. They were finally fully trained at 1 year. It takes a lot of time, especially when you have one trained and then get a new little baby, like we did. I was training for over a year. We are finally done, though.
One piece of advice; when we were not home we would keep them crated. When we were home, they weren't allowed to be out of the crate but ONLY in the area that we were so that we could catch them in the act. I had to constantly take them out to potty to make sure they didn't have any accidents! Now I put them out about every 2 hours....they have small bladders and we just have to be patient.