Sunnah of the day!!!
Surah kahf may be read during the night or the day of Jumu’ah.
The night of Jumu’ah starts from sunset on Thursday,and the day of Jumu’ah ends at sunset.
Therefore the time for reading this Surah extends from sunset on Thursday 2 sunset on Friday
(al-Targheeb wa’l-Tarheeb,1/298)