When should Muslims start takbir on Dhul-Hijjah, and what is the exact wording transmitted from the Prophet (peace and blessings be upon him) in this regard?

I have the habit of fasting every Monday and Thursday. I heard that it is not permissible to fast on the Days of Tashreeq (11, 12, and 13 Dhul-Hijjah). I fasted one of the Days of Tashreeq.

Dhul-Hijjah 9 is a very special day. The Day of Arafah, one of the most blessed days of the year, is named after the place where pilgrims gather on this day, `Arafah. Rituals of Dhul-Hijjah 9 After the sun rises on Dhul-Hijjah 9, pilgrims leave Mina to `Arafah. Staying in `Arafah is a major pillar …

The aim would be to try and make the best use of this day if possible, and we will suggest a routine, which would be possible even if one is busy Insha’Allah. So here is the routine. Wake up Early and pray Tahajjud and Have Suhoor. Make lots of du’a during the Tahajjud time…

Can you, please, mention the days of fasting in Dhul-Hijjah? What is the evidence?

Is the sacrifice of a person who cut his hair and trimmed his nails after the beginning of Dhul-Hijjah valid under such circumstances?

What are the references for performing good deeds (especially fasting) on these days?