Related for Avodah Zarah 10:15

[If] the portion of the Shekalim fell [as part of the normal cycle] next to Adar, either before it or after it, we read it [at its normal time] and then we read it a second time [for purposes of Purim], and so two for the second [portion], and so too for the third, and so too for the fourth. And so too for Chanukah (בחנוכה not בפורים). They ask about the halachot of Passover on Passover, and the halachot of Shevuot on Shevuot, and the halachot of Sukkot on Sukkot. In the study hall they ask about the halachot of Passover thirty days before Passover. Rabban Shimon ben Gamaliel says, two weeks.