I can probably answer this question as I did gain 2 cup sizes with NB that are permanent. I pumped continously for a good 9 months, took breaks only for a week at most until a year, then I slowed down more and more and stopped. I stopped completely last year in August or so, maybe September, hard to remember. And I was a 32D without swelling, I am still a 32D and the size I was without swelling when I stopped completely. And I hadn't pumped since then except for tonight I pumped for the first time since then. Hope this helps to make it clear the time commitment you would need to do.
Ladies, you cannot compare Brava with NB. Brava is a system that has to be worn 10 hours a day!!! That is why it might deliver permanent results faster. But with continued use of NB, your after swelling goes down size can become permanent. It might not be permanent after a week or even a month. But give it a good 6 months to a year and it will gradually become more and more permanent, and your after swelling goes down size will become more and more. Hope this clears things up.