How do you know when to start potty training?

C 🖤

My son is 15 months old and has recently started pulling at his nappy when he's doing a wee, and then will keep pulling at it or pointing at it like it's uncomfortable until we change him. He likes to stand and watch the bath fill up so we've been letting him do that lately and will get him naked ready to get in while he's waiting, and a few times this week he's waited until his nappy was off and then done a wee next to the toilet.

It seems way too early but are these the early signs that he's getting ready to ditch the nappies?