All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Muslim scholars are of two opinions concerning the time difference of the new moon.
The majority of the Muslim scholars are of the opinion that the difference in sighting the new moon is not considered.
If the Muslims in any region in the world see the new moon, then all Muslims in the rest of the world should follow them. They based their opinion on the Hadeeth of the Prophet in which he said: “When you see the new moon, observe fast, and when you see it (again) then break the fast, and if the sky is cloudy for you, then complete thirty days for the month of Sha'ban.” [Al-Bukhari and Muslim]
The Shaafi'i School of jurisprudence take into consideration the time difference in sighting the new moon. We believe that the opinion of Shaafi'i School is preponderant in this issue. However, we advise Muslims to avoid what could cause dissension, difference and disputes among them. Allah Says (what means): {And hold firmly to the rope of Allah all together and do not become divided.} [Quran 3:103]
Therefore, we would like to advise Muslim brothers to follow the decision taken by the Muslim scholars in their country.
If the Islamic center in your region has decided to consider the time difference in sighting the new moon you have to follow them. The Prophet said: “The fast begins (month of Ramadan) when all of you (Muslims) observe the fast, the fast ends when all of you end it, and the Eed al-Adha is when the Muslims offer their sacrifice.” [Abu Dawood]
As for the one who performs Hajj or goes to another country, he/she should follow the Muslims of that place.
Allah knows best.