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.
The month of Ramadan (or any other Islamic month) starts only by sighting the new moon or by completing thirty days of Sha'ban month, if the moon is not seen. The Prophet said: “Fast after you have seen it (the new crescent) and end the fast (at the end of the month) when you see it again. If it is hidden from you (i.e. if it is cloudy), then wait until the thirty days of Sha'baan have passed.” [Al-Bukhari and Muslim] According to the calendar this year Ramadan will start on 26th of October 2003. However, the criterion is sighting the crescent of Ramadan or completing thirty days of Sha'baan.
Allah knows best.