I have the advantage that I work from home and am with my baby girl all day, but I noticed she was like clockwork (if I was consistent)...
Morning, upon waking up...Her breakfast... Then immediate walk, pee, and poop.
Early afternoon... Walk and pee.
Late afternoon... Her dinner.
Evening... Walk, pee and poop. Then a treat.
I am absolutely consistent when I feed her... The same exact times every day.
In the beginning I watched her like a hawk... When she left my side and didn't go for a drink of water, I knew she was up to something... As soon as she started to wander or circle... I would say "Ah, ah, ah!" ("No" is only for misbehaving). Then I would hurry her out the door with a leash... Whenever she peed or pooped outside I'd praise her effusively... If she had an accident inside... I'd just ignore it (and her) and clean it up. She lives for praise, and eventually learned to give me "the stare" when she wanted to go outside.
I was surprised how easy it was to train her (two weeks at most)... I've been told that it's because I was consistent and adapted my behavior to HER schedule.
She is my first dog, and I've had her nine years. She's perfect.