No Postponements During Temple Times
The Mishnah is the written record of Jewish oral law, relating to the Torah and Jewish customs, handed down from time immemorial -- from the days of Moses. These "oral laws" were written down and compiled in about 200 A.D., in narrative form, in the centuries after Christ, to insure that they would never be lost or forgotten. The Mishnah itself was part of the Talmud, a larger body of Jewish tradition and interpretation and history of Jewish thinking and commentary. It was compiled, therefore, about 158 years before the rulings of Hillel II!
What does the Mishnah say about "postponements" in the time of the second Temple period, or the time of Christ? Notice! In The Mishnah, a New Translation, by esteemed Jewish professor Rabbi Jacob Neusner, we read in "The Second Division: Appointed Times," under "Shabbat 19:5":
A. An infant is circumcised on the eighth, ninth, tenth, eleventh or twelfth days [after birth].
B. never sooner, never later.
C. How so?
D. Under normal circumstances, it is on the eighth day.
E. [If] he was born at twilight, he is circumcised on the ninth day.
F. [If he was born] at twilight on the eve of the Sabbath, he is - circumcised on the tenth day [the following Sunday].
G. In the case of a festival which follows after the Sabbath, he will be circumcised on the eleventh day [Monday].
H. In the case of the two festival days of the New Year [ROSH HASHANAH, that is, Tishri 1-2], he will be circumcised on the twelfth day [Tuesday]" (The Mishnah, p.203).
Did you notice that last ruling? Clearly, it states that Rosh Hashanah -- Tishri 1 -- could fall on the first day of the week -- Sunday! Since the Jews observe two days for Rosh Hashanah, Tishri 1 and 2, this means that the New Year could fall on Sunday and Monday, causing circumcision of a child born on the eve of the weekly Sabbath a week before Rosh Hashanah (that is, late on Friday) to be deferred until twelve days later -- a Tuesday -- if Rosh Hashanah fell on a Sunday, that year.
Clearly, the postponement of Rosh Hashanah ITSELF from Sunday to Monday was NOT DONE during Temple times, or the Mishnaic period! This postponement was an entirely NEW addition to the law -- a NEW regulation -- devised by Hillel II and his compatriots, in 358 A.D.! But let's notice another example from the Mishnah. In the Mishnah section titled, "The Fifth Division: Holy Things," under "Menahot," we read the following: 
"R. [If] the Day of Atonement coincides with the Sabbath, the loaves [of the showbread in the Temple] are divided in the evening.
S. [If] it coincided with the EVEN OF THE SABBATH, the goat of the Day of Atonement is eaten in the evening" (p.758).
Did you notice? The Day of Atonement, during Temple times, could and did occur on the "eve of the Sabbath" -- that is, FRIDAY! Therefore, Dechiah "a" forbidding the Day of Atonement to occur on a Friday was not observed in Temple times, and is null and void, as far as the Law of God is concerned! It was only added about three hundred years AFTER Temple times because of unjustified concerns about having two days in a row in which no food was to be prepared!
Here is another example from the Mishnah, showing that the ruling concerning Hoshana Rabbah was also a new invention by Hillel II and was not observed in Temple times. Again, in the section of the Mishnah titled "The Second Division: Appointed Times," under "Sukkah," we read the following:
"4:1 A. [The rites of] the lulav and the willow branch [carried by the priests around the altar, M.5:5] are for six or seven [days]. . . .4:3 A. The willow branch rite is for seven days: How so? B. [If] the seventh day of the willow branch COINCIDED WITH THE SABBATH, the willow branch [rite] is for seven days . . .4:5 F. And on that day [the seventh day of the willow branch] they walk around the altar seven times. . .4:6 A. As the rite concerning it [is performed] on an ORDINARY DAY, SO THE RITE CONCERNING IT [IS PERFORMED] ON THE SABBATH" (page 286-287).
Notice! This is talking about the seventh day of the Feast of Tabernacles, or "Sukkot." The seventh day is known as Hoshanah Rabbah. During Temple times, this day could and often did coincide with the weekly Sabbath! When it did so, the rites of the willow branch and lulav were performed AS THEY WERE ON AN "ORDINARY DAY"! So states the authoritative Mishnah itself!
Clearly, then, the changes wrought in the calendar in the days of Hillel II concerning the postponement of "Dechiah a" were an innovation not supported by Scripture, nor were they observed in Temple or Biblical times. They constituted a DEPARTURE FROM THE LAW of Almighty God! They were unholy, unwarranted, and sacrilegious! Because of them, millions have been keeping God's annual Holy Days on the wrong day, for centuries, and even down to this present time!