One of Artscroll's "Daily Dose of Torah" books, on parshat Vaera, says that the Israelites stayed in Egypt for a significant period of time after being freed from slavery but before the Exodus. I never heard that before. Is there a source for it?
It is a statement for R' Eliezer in the Talmud, Rosh Hashanah 11a, at the very top of the page. There he says that the slave labor and subjugation of the Jewish People stopped in Tishre, and the Jews were Redeemed in Nissan.
R' Yehoshua, who argues with some of the points R' Eliezer made there, agrees with this timeline.