Instances When Intercourse is Permissible and When Not Permissible 

1. A woman has a cycle of 5 days haidh, or 9 days. According to the cycle the bleeding occurred, and then ceased. Now she has to compulsorily have a ghusl to have coition with her husband.
2. If she does not have a ghusl and one Namaaz time passed by, that is the Namaaz became Qadha, then too coition will be permissible, not before that. (She is, however, sinful if she did have the time to have a ghusl and perform her Salaat, yet she made it Qadha.)
3. If her cycle was 5 days and the bleeding stopped on the 4^th day, then it is waajib to have a ghusl and perform Salaat.
4. Coition in the above case (3), however, is not permissible, as long as 5 days are not over, for it is possible that the bleeding resumes.
5. If haidh lasted for 10 complete days then upon the bleeding terminating copulation will be permissible, whether she had a bath or not.

(Behshti Zewar)