Any advice?

My son is 15 months and he just started pulling his diaper off whenever he pees in it and wants it to be changed but he still hasn’t tried to start talking more than his normal dada, baba, mama, get, and kitty. So I’m not exactly sure if I need to start showing him where we will keep his potty when we get it or if I need to buy one now. At his grandparents house they have a potty for his older cousins and he loves banging on the lid, opening and closing it, and helping me close the big boy potty when he’s in there with me. I’m just clueless on what I need to do next and my parents are telling me I needed to start once he turned a year old.