Related sur Ta'anit 1:3

From when do we start asking for rains? From when the time of the rains comes. If it was a lacking year (meaning, a year with 353 days as opposed to 354), we give it its lack (the extra day it should have had). If not, it goes according to its set schedule: [All of this goes by] the words of Rabbi [Yehudah haNasi]. Rabban Shimon ben Gamaliel says, "Actually, they go according to their set schedule [all the time]." If it was a leap year, we give it its extra.

What is considered the first rain (heb. R'viah)? [Rabbi Meir says, "An early one (lit. a firstborn) [falls] by the third [of Marcheshvan]; a middle one [falls] by the seventh; [and] a late one (lit. a dark one) [falls] by the seventeenth." Rabbi Yehudah says, "An early one [falls] by the seventh; a middle one [falls] by the seventeenth; [and] a late one [falls] by the twenty-third." Rabbi Yose says, An early one [falls] by the seventeenth; a middle one [falls] by the twenty-third; [and] a late one [falls] by Rosh Chodesh Kislev."] And so, Rabbi Yose would say, "The individuals do not fast until Rosh Chodesh Kislev."