Started potty training over week ago. He can do a wee and occasionally a poo when i ask him or take him to the toilet. But if I don't ask he does it where ever he is on sofa, at table. He has a potty in lounge but never uses it. I reward him with sticker and chocolate. But he nver asks to go. How do I get him to tell me he wants to go. He is 3yr in sept. Any advice please.