We use the "puppy pads" to help the puppies get the idea that there is a special place "where" they should go... which is the first step to fully house trained. We are not experts in this, but we think the maturity required for the puppy does not kick in until after weaning, which is just happening... we can see the puppy-maturity changing almost daily.
Up until the puppies stop nursing and are weaned, the puppies believe that they are "part" of the mother (and a few short weeks ago they were!). During this time (nursing), the mother controls even 'potty training' in her own doggy way. Our puppies stopped nursing at about 6-1/2 to 7 weeks and the mother took the lead on this (see the second video). So the puppies are just weaned, and they are just maturing and beginning to understand that they are now their own (puppy) person (no longer part of Mom), and so they are just learning that with this independence comes certain (puppy) responsibilities to the humans in their lives (the 'pack').
A characteristic of the Bernese, is that they come to believe that they are part of your family (or, from Bernese puppy perspecitve, you are part of their 'pack').
We have worked to socialize your puppy... and that includes working on potty habits. We spend one-on-one time with each puppy... but with eight puppies that fun task is limited in time... and when we do have them individually like that, we watch and listen for the signs of 'needing to go' (like trying to get out of your lap, acting anxious, panting), and we take that opportunity to direct them to the puppy pad which is in the entry way. With multiple puppies it gets more difficult (see the most recent video "Video #2"))... although the puppies generally do ok at finding and hitting the puppy pad... or close to it. :)
Bernese do not like to go potty in their habitation, so training them is just taking advantage of this momentum and encouraging them.
You will be completing this training. One big advantage to this is that, it will be individualized based on the way you communicate, the way your home is organized, and exactly what expectations you have for your puppy.
A note about Bernese puppy training and discipline... we have read, and it is our experience, that the Bernese responds almost 100% to positive reinforcement. The strongest negative discipline we have ever used with Shiloh is to ignor her, which is sort of "neutral discipline". We encourage you to read up on this side of the breed. Bernese are like no other dog, which is why they are so loved. (There are good links elsewhere on the blog. )
Anyway, that is my thinking on the Bernese Mountain Dog, based on what I have read, based on what our daughter has told us, and based on our experience.