From the invaluable Merriam-Webster dictionary:  

Tickler  noun

1: a person or device that tickles. 

2: a device for jogging the memory; specifically: a file that serves as a reminder and is arranged to bring matters to timely attention.

Most scribes employ No. 2 to some extent, whether with old-style manila folders or in electronic form. Attention to the calendar paid off with a Feb. 19 feature by the Pittsburgh Post-Gazette’s well-respected Peter Smith on the 50th anniversary of the local “Duquesne Weekend,” which inaugurated the Catholic Charismatic movement.

Further examples: 

Political reporters’ datebooks will mark the 100th day of President Donald Trump’s presidency, or perhaps the July 20 half-year point, as useful points to assess the new administration. Another peg comes June 14 when history’s oldest president turns 71 (while refusing to provide full medical data, as with his tax returns).

Religion beat specialists could use those same calendar pegs to examine  pro and con reactions to how the new president is handling questions of keen religious interest, overtures to this or that religious faction, or whether he ever attends church services, if so where, and if not why. Or this: Is the liberal Christian Century correct that Trump has obliterated the “civil religion” preached by prior presidents?

Speaking of presidents, ticklers will list the National Prayer Breakfast the first Thursday of each February. The 2017 version roused great expectations after a religiously and morally bizarre campaign, and President Trump’s first outing did not disappoint. He recalled childhood “in a churched home,” suggested prayer might help Arnold Schwarzenegger achieve his own “tremendous success” on TV, and remarked “the hell with it” during a fond mention of the Senate chaplain.