Is it Sunnah to cut the nails?
What is the way and the time or day that is best for cutting nails?
The majority of scholars agree on this hadith:
And he (may Allah have mercy on him) said in Sharh Saheeh Muslim (3/149): It is mustahabb to start with the hands before the feet, and to start with the forefinger of the right hand, then the middle finger, then the ring finger, then the pinkie finger, then the thumbs, then to move to the left hand and start with the pinkie finger then the ring finger, until all the fingers are done, then to move to the right foot and start with the smallest toe on the right foot and end with the smallest toe on the left foot. And Allah knows best.
You can read the full fatwa here.