T.K.
Hi there!
My oldest son was 27 months when he was fully trained. He had started telling me when he was wet and so I knew it was time. He trained ina week and never looked back. Easy!
My youngest son took forEVER. I started him around 29 months but could see he wasn't ready and then around 33 months pushed it again and persisted. It took over a month for him to get the hang of it (he is very strong willed!). Truly could not have been two more different experiences.
With both I read a lot of potty books and set a timer to go off and took them every 30 minutes or so at first. I had to definitely maintain my patience and limit my level of frustration I showed with my second. That is what finally helped :)