My Maddie is two. I have a large fenced yard and found that there was too much distraction. I purchased a small x-pen and we started actually picking her up inside and carrying her to the pen, placing her in the pen to pee and poop. This served multiple purposes. Her scent was really strong in the small area so she would pretty much go right away. One of us always takes her out so we know for sure if she goes or not. There are also no distractions so she pretty much knows to take care of her business if she wants out. We often let her out to run around the yard after she has taken care of business, so sometimes that is a treat as well. If I have time, I sometimes would just let her run around the yard, but even then, watched her like a hawk and would praise her whenever I saw her squat. She will pee and poop first thing in the a.m. and right after eating supper and about every 4 hours in between. When I know it is poop time, I just keep her in the x-pen, tell her good girl after she pees, then say go poopie and then ignore her until she does. Sometimes I think we use to not give her enough time and she would come in the house and then poop!
With the shape of my house, the bells would not work since there are parts of the house you wouldn't be able to hear them. I started getting Maddie to bark before we walked outside. I did this by "barking" at her
, I know, I'm nuts, until she would bark back at me. When she barked, I would say good girl, lets go potty and did this EVERY time. Now, when she needs to go out, she will bark and let us know. However, I don't rely on this alone. If it's been 4 hours I will take her out to pee even if she isn't barking. If she doesn't go, I take her every 15 min or so after that until she does go. I do crate her if we are going to be gone from the house for more than 4 hours so she doesn't have the chance to have an accident.
BTW, she is 7 lbs and I came up with the 4 hour time by actually writing down the times she went potty until I could figure out her schedule. Just like a baby!