What is the preferred timing for performing dry ablution (Tayammum) and prayer when water is absent?

Primary text

Dry ablution is preferable in all circumstances, which is the established position (Manṣūṣ) from Ahmad. This view is narrated from Ali, Ata, Al-Hasan, Ibn Sirin, Al-Zuhri, Al-Thawri, and the People of Opinion (Ashab al-Ra'y). It is preferable to delay the prayer if one hopes to find water, but if one despairs of finding water, it is preferable to perform the prayer earlier. This latter view is attributed to Malik. The rationale for delaying is similar to delaying prayer after necessary cleansing or until after Isha' to maintain focus and heart presence, and delaying to catch the congregation; thus, delaying for the condition of purity is considered more worthy within the time frame.