1,399. Residents of Small Villages

Hilchos Megillah v’Chanukah 1:6

The Sages decreed that the residents of villages, who would only congregate in shuls on Mondays and Thursdays, could read the megillah earlier, on the day when they would normally meet. Therefore, if 14 Adar fell on Monday or Thursday, they would read the megillah on that day, but if it fell on other any day, they would read it earlier, on the Monday or Thursday closest to 14 Adar.

Hilchos Megillah v’Chanukah 1:7

Accordingly, if 14 Adar fell on Sunday, the megillah is read on the preceding Thursday, 11 Adar. If 14 Adar fell on Tuesday, the megillah is read on the preceding Monday, 13 Adar. If 14 Adar fell on Wednesday, the megillah is read on the preceding Monday, 12 Adar. Whenever permission has been given to read the megillah earlier than 14 Adar, it may only be read in the presence of a minyan.