I wish I could help you but mine arent on much of a schedule, except for the mandatory morning, evening and night runs....
I always just try to make sure that they have a sufficient amount of time after eating to wander around and decide the "perfect" spot... I have a small side yard where the always go "pee pee" and then I take them on leashes every morning and afternoon when we go "outside"... I have always found that using a specific word for pottie time makes them recognize the tone and know that it is time to do their business...
Good Luck to you!
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