At what point does one start praying the Lunar Eclipse Prayer?

Imam Al-Dardir and Al-Dusuqi mention this in Hashiyat Al-Dusuqi.

It is when the light of the moon is noticeably reduced- whether the moon is totally covered or partially. If the light is disrupted negligibly, then the prayer is not recommended yet.

Written by Uthman Qureshi

References:

Al-Sharh Al-Kabir

، وَأَصْلُ النَّدْبِ يَحْصُلُ بِرَكْعَتَيْنِ وَمَا زَادَ فَمَنْدُوبٌ آخَرُ (لِخُسُوفِ قَمَرٍ) أَيْ لِذَهَابِ ضَوْئِهِ أَوْ بَعْضِهِ

Hashiyat Al-Dusuqi

(قَوْلُهُ أَيْ لِذَهَابِ ضَوْئِهِ أَوْ بَعْضِهِ) أَيْ مَا لَمْ يَقِلَّ الذَّاهِبُ جِدًّا وَإِلَّا لَمْ يَصِلْ لِذَلِكَ

Source: Hashiyat Al Dusuqi ala Al-Sharh Al-Kabir ‘Ala Mukhtasar Khalil. Dar ul Fikr, pg. 402/1.