Do the twelve rak'ahs of supererogatory prayers (nafl) begin from the Sunnah of Fajr until Isha, or from the Sunnah of Dhuhr until Fajr, as mentioned in the hadith that they begin with the Sunnah before Dhuhr?

The intent of the hadith is to encourage Muslims to consistently perform twelve rak'ahs of voluntary prayers daily and nightly. It is authentically reported in Sahih Muslim from Umm Habiba that the Prophet, peace and blessings be upon him, said: "There is no Muslim servant who prays to Allah twelve rak'ahs voluntarily every day, other than the obligatory prayers, but that Allah will build for him a house in Paradise."

Other narrations have clarified these rak'ahs. An-Nasa'i and At-Tirmidhi added in the hadith of Umm Habiba: "Four before Dhuhr, two after it, two after Maghrib, two after Isha, and two before Fajr prayer." Other narrations mention a different order of these rak'ahs, with some presented earlier or later.

There does not appear to be any issue with starting the count from a specific prayer, as the conjunction "wa" (and) does not necessarily imply order, according to the sound opinion.

The correct view is that the first prayer of the day is the Fajr prayer.