with my DD I accidently bought the wrong sized nappies for her when she was barely 2 and she refused to wear them, so she went into knickers. She was dry day and night from that day on, however doing poo's took nearly 12 months more to get the hang of.
DS was also 2, and I knew he was ready. I told him one day that I was not putting on nappies anymore and he had to go to the toilet, never wore nappies again.

I have a friend whose DD TT at 16 months, she just left a potty out and her DD would just take herself off to the potty when she needed it.

If I were you I would try now, with summer its so easy to leave them with just undies on, so you only have one thing to wash out if they have an accident

Good luck