When did the word poop change to poo?

When I was a small child and I had to poop, I told my mother I had to do a #2. That was really a poop, except my mother didn’t want me shouting poop in the middle of a store, so her code word for poop was #2.

Now I’ve been hearing the new-improved, shortened version of poop being used, which apparently is poo.

I don’t know about you, but I have poo-pooed an idea or a piece of advice from time to time, but I’ve never pooed on a toilet, as far as I know.