When does the state of Ihram begin: on the first days of Dhul-Hijjah or a day before, and when does a woman in menstruation enter the state of Ihram?

It is permissible to enter into the state of ihram for Hajj before the months of Hajj, though it is disliked, and its validity is the opinion of most scholars. It is also permissible for a menstruating woman to enter into ihram for Hajj, and she may perform all the rituals of Hajj except for circumambulation (Tawaf).