Today’s date is Monday 2nd Sha’aban 1445AH = 12th February 2024.

The basic ruling in Islam is to search for the moon (that signals the beginning of another Lunar month) when the current month (i.e. Sha'aban in this case) is 29. If the moon is sighted then Ramadan starts!

Otherwise the current month (of Sha'aban) is counted to 30 days and then the next month (of Ramadan) starts after.

So Sha'aban 29th will be Sunday 10th March 2024.

If the Sultan announces the sighting of the moon by Sunday Sha'aban 29 (10th March, 2024) evening then we start fasting on Monday 11, March 2024.
If the moon wasn't announced to be sighted then Sha'aban will be counted to 30 days.
Fasting then starts on Tuesday 12th March 2024.

Evidence: Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (May Allah exalt his mention and protect him from imperfection) said: “Fast when you see the new moon (of Ramadan) and break your fast when you see the new moon (of Shawwal.) If clouds prevent you from seeing it, complete thirty days in the month of Sha'aban (the one that precedes Ramadan). (Al-Bukhari and Muslim).

Commentary: (…) If the moon of Ramadan is not sighted on the 29th Sha’aban, then its thirty days be completed and Ramadan’s Saum be started on the next day. Similarly, if the moon for the month of Shawwal is not sighted on the 29th of Ramadan, thirty days of Saum must be completed before celebrating ‘Eid-ul-Fitr. This means that the sighting of the moon is necessary for keeping the Saum of Ramadan. Counting by celestial system is not sufficient for this purpose. (…)
Riyaadiss-Saliheen (The Meadows of the Righteous)
By Imam An Nawawi
Chapter 217, Page 356, No 1221
https://www.salaattime.com/hadith-fast-when-you-see-the-new-moon-of-ramadan/

Note: Each country is expected to sight the moon for Ramadan! Nigerians are not to use the moon sighting in Saudi Arabia to start Ramadan!

Evidence: Kurayb repoted: I came to Syria and tended to my needs. The crescent of Ramadan appeared over me while I was in Syria and I saw it on Friday, then I came to Medina at the end of the month. Abdullah ibn Abbas, may Allah be pleased with him, asked me about it and I mentioned the crescent. Ibn Abbas said, “When did you see it?” I said, “We saw it on Friday night.” Ibn Abbas said, “You saw it?” I said, “Yes, people saw it and they fasted, as did Mu’awiyah.” Ibn Abbas said, “But we saw it on Saturday night, so we will continue fasting until we complete thirty days or we see it.” I said, “Is it not enough that Mu’awiyah saw it and he fasted?” Ibn Abbas said, “No, such was the command of the Messenger of Allah, peace and blessings be upon him.” Source: Ṣaḥīḥ Muslim 1087
Grade: Sahih (authentic) according to Muslim

Al-Tirmidhi said, “The people of knowledge act upon this tradition, that the people of every land have their own moon sighting.”
Source: Sunan al-Tirmidhī 693

In summary
If the moon is sighted by Sunday evening of Sha'aban 29 1444AH (10th March, 2024) then Ramadan starts on Monday 11th March 2024.
If the moon wasn't announced to have been sighted on Sunday evening of 29 Sha'aban 1444AH (10th March, 2024) then Ramadan starts on Tuesday 12th March 2024.

May Allah accept all our good deeds, pardon us our sins, heal the world of illness/Wars, grant succor to the distressed, forgive our dead and Grant us Jannah without stress.

Ameen Ya Hayyu Ya Qayyum.