It is Mustahab (preferable) to delay the Esha Salaah to one third of the night. Rasulullah (صلى الله عليه وسلم) said “If I did not fear difficulty upon my Ummah, I would have commanded them to delay the Esha to one third of the night. It is Mubah (permissible) to delay Esha Salaah unto half of the night. To delay it to after half of the night is Makrooh (reprehensible) (Tahtaawi Page 184 Ilmiyya).
And Allah knows best
Muhammed Zakariyya Desai,
Checked and Approved by:
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah