when should i change my dog wee wee pad?

You should change to not using them unless you're talking about a handicapped or sick dog that REALLY can't hold it. You're DISGUSTING. I can't imagine what your home smells like.

To answer your question - when you piss and poop in the toilet do you just leave it there for a day or two?

never , train your dog to go outside

When it has been peed on. But i suggest walks instead. Pads teaches the pup that it is okay to wee indoors.

You shouldnt you should dump the pathetic rubbish. The correct way to housetrain a dog is to take it on frequent walks both in daylight and nightime hours...... With the pathetic pad you are in fact teaching the dog it is perfectly ok to soil your and its home

Throw them away and stop being lazy teaching your dog to pee inside the house as once you have done that the dog will decide where it wants to pee inside the house and you will always have a house that stinks of dog pee and a dog that is not trained to toilet outside

You shouldn't be using them. This only teaches your dog that it is ok to pee indoors. Take the dog out in the garden for pees and then you won't have to worry about housetraining later.