How can we determine that “Naadi Shuddhi” has taken place successfully when we practice Naadi Shuddhi pranayama? How many days of practice does it require to successfully implement it?
Kindly provide the complete details.
Thank you.
Welcome to the Forum.
To answer your question: Nobody can really tell you how long it will take you to implement the practice, because we have very little info about you and no direct contact. You neither telling us if you attempt this on your own or with a teacher? It can take you a day, a week, a life time or even many incarnations. Point is we simply don’t know, because we don’t know where you are spiritually, how dedicated and committed to your path you are, what yoga did you do sofar etc.
It would constitute short sightedness for me to want to meassure the success of your progress in any of the yoga practices in terms of days, weeks or months. Just do it and watch as you unfold in front of your own eyes and enjoy the beauty and wonder that comes with that unfoldment, no matter how long it takes.
Trust this will shed some Light. 
Here lies the beauty of Yoga, it is not merely a simple excercise. With it, lies many other things which are as important as the process of exercise, like your concentration level, your spiritual level, your commitment, your diet etc etc. So the only way to know the difference is to feel it. Normally people start feeling “shuddhi” being done within a week but it requires good amount of concentration to make it successful.
^very nice answers