In the first place, we would like to stress that I`tikaf is a Sunnah and according to many jurists it is a confirmed Sunnah (Sunnah Mu’akkadah) upon able Muslims. This is because the Prophet (peace and blessings be upon him) used to do it all his life and the Mothers of Believers and the Companions continued to do it after the death of the Prophet.
On this, a prominent Azharite scholar Sheikh `Abdul-Majeed Subh, states that:
Muslim woman is permitted to make I`tikaf in her home in a room where she can have a secluded time with herself engaging in Dhikr and Qur’anic recitation. she can do it during the night to the best of her ability.
As for the time of the start of the `Ibadat, I can say that the day according to Islamic Sharia ends with Maghrib time, hence after Maghrib, a new day begins. Thus, the next fasting days begins after we break our fasting for today at the Maghrib time.’