Are the times for seeking permission mentioned in the verse, "O you who have believed, let those whom your right hands possess and those among you who have not reached puberty ask permission of you three times," the preferred times for intercourse, and is it permissible to have intercourse at times other than these, such as after the Fajr prayer, if it is the only available time?

There is no blame on the husband for having intercourse with his wife after the Fajr prayer or at any time he wishes. The mentioned verse does not indicate a preference for intercourse at these times. Rather, it concerns the permissibility of seeking permission during them, which are: before the Fajr prayer, at noon, and after the 'Isha' prayer, due to the concern of uncovering private parts during these times.