Answer
(Fatwa: 105/91/B=1433)
The best time of intercourse is last part of the night. You should perform ghusl immediately after having intercourse and then offer salah. If you fear that your sickness shall increase due to having ghusl in the night then you should have ghusl with warm water in some closed place. You can have intercourse any time during day. You also can have intercourse after Fajr as well. However, it is severe sin to miss Fajr salah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband