Teddy is 4 months old and has gone a week accident free. It has been a month since we got him. We only do outdoor training though, and since we got him use to house training bells, he is doing REALLY well.
What i've learned is just stick to a schedule. Don't deviate, I forget the phrase but it's like it takes x amount of days to form a routine and x amount of days to form a habit. Dogs are creatures of habit and love routine, you can't just change it up and expect them to understand.
We use housetraining bells,his crate, and of course he's under my constant eagle eye
I've been consistent and i'm seeing results as early as a month into training.
Good luck!