There is no particular time for performing iʿtikāf; rather, whenever it is correct (ṣaḥiḥ) to keep a fast (ṣawm) during the year, performing iʿtikāf at that time is also correct. The best time for performing iʿtikāf is the blessed month of Ramadan, more so during the last ten nights of the month of Ramadan.