The lunar months are established either with a lapse of 30 days or when the crescent of the new month is sighted. When it comes to the beginning of a lunar month, it does not make any difference whether it is the month of Ramadhan or Muharram etc. Therefore, unless one of these conditions (lapse of 30 days or sighting of crescent) is available, one cannot decide as to what day the first day of the month is.
Sighting of the Crescent and Issues Related to It, 9927 (site: 10082).
Establishing the Beginning of the Month by Sighting the Crescent with Equipped Eyes, 6153 (site: 6285).