1,250. When They Sent Messengers
Hilchos Kiddush HaChodesh 3:9
Messengers were sent to inform people regarding six months: for Nisan because of Passover; for Av because of Tisha b'Av; for Elul because of Rosh Hashana, so that they could be ready on 30 Elul. If it became known that the court had sanctified the 30th day, only that day would be observed as a holiday, otherwise both the 30th and 31st days would be observed until the messengers for the month of Tishrei arrived; for Tishrei because of the holidays; for Kislev because of Chanukah; for Adar because of Purim. While the Temple was standing, messengers were also sent for Iyar because of Pesach Sheini.
Hilchos Kiddush HaChodesh 3:10
The messengers for Nisan and Tishrei would not leave until the sun had risen and they heard the court announce, “It is sanctified.” If the court sanctified the moon at the end of the 29th day and the messengers heard them declare it sanctified, they could depart that night. The messengers for other months could depart at night after the moon was observed. Even though the court did not sanctify the new month, because the moon was not seen, they could go because the court would certainly sanctify the month on the next day.