My son will be 3 in February. We've bought him a book called "pirate Pete's potty" which has helped him show an interest but he's still wearing nappies. He tells me (most of the time) that he's going for a poo and usually goes off on his own and says "GO" if you go near him. He's sat on the potty a handful of times for a few minutes. I'm really not stressing about it.