Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

There are so many views on how long Itikaf can be. So you can do Itikaf even one day or half day if you wish.

I suggest you do it the last days of Ramadan with the night of Qadr included on the 27 for the great rewards in that night.

During their menses, women can read the Qur’an and make dhikr (remembrance of Allah) and du`a’ (supplication), though they are forbidden from fasting, performing prayer and touching the mushaf (copy of the Qur’an). In this way, they still have the opportunity to observe Laylat al-Qadr (the Night of Power) by reciting the Qur’an and making dhikr.

Almighty Allah knows best.