Elijah will not come until the generation is entirely guilty or entirely righteous.
-Midrash Tanchuma, Vayeira 6
At the end of days, Elijah will stand on the mountains of Israel and blow the great shofar, proclaiming the time of redemption.
-Pirkei DeRabbi Eliezer, Chapter 11
In Nisan they were redeemed, and in Nisan they will be redeemed in the future.
-Talmud, Rosh Hashanah 11a