Here's what I have done:
every time she has slept, eaten or played I take her outside for a walk of 20 minutes. I bring treats and everytime she pees or poops I give her one followed by "Gooooood dog, you're such a gooooood dog" and big smile
I walk her as the first thing in the morning and as the last thing before I go to sleep. I walk her as soon as I get home - and after 3 months she was hoursebroke
Now I just let her out into the garden at the times where I would have walked her - she does the rest
I do take her for a walk now and again - she loves to snif around the neighbourhood and it is much more challinging for her to snif than to stay around the house all day