In the name of Allah, the most Beneficent, the most Merciful.

Answer

If a person has received a blessing or a favour from Allah (SWA) or some difficulties or hardships have been eased, then it is Mustuhub (desirable) to read Salat Shukr. There isn’t a specific number or rakaats one should read, however, two rakats should be the very least. (Fatawa Mahmoodiyah p.125 v.7)

As Salat Shukr is Mustuhub it holds the same ruling as an optional prayer. Therefore, it will be Makruh to read this salah after Fajr and Asr prayers. Similarly, when the Fajr prayer begins no other Nafl prayer is permissible except the two rakaats of Sunnah Fajr and two rakaats of Farz Fajr. Also this prayer is not in order at the time of rising of the sun, noon and sunset. (Maraqi Falah P.74)

With regards to your question it will be permissible to read Salat Shukr after Ishaa prayers.

Only Allah Knows Best

Mohammed Tosir Miah

Darul Ifta Birmingham.