http://classic.7sage.com/lsat_explanations/lsat-66-section-3-game-1/

For this game, the instructor said "J" and "O" can't be stacked together because the rule is: "J" comes earlier than "O." If "J" is stacked with "O," with "J" in the a.m. and "O" in the p.m., isn't that still J - O?