QUESTION: Is there a specific time after the funeral when the tombstone should be set? Must one wait twelve months, or may this be done sooner?
ANSWER: There is no fixed time period which must elapse before the tombstone may be set. It has become customary among some modern Orthodox Jews to wait twelve months (Akiva Eger, Hidushei to Shulhan Arukh Yoreh Deah 376.4). However, there are many opinions which state that the tombstone may be set as early as the conclusion of the shivah period (Tos. to Ket. 5a). In fact, a mournermay interrupt the period of mourning to concern himself with the tombstone (Sifsei Kohen to Shulhan Arukh Yoreh Deah 375, note 12). In Israel tombstones are often erected at the end of the thirty days of mourning (sh'loshim).
Greenwald, after citing all the customs which have been followed in both ancient and modern times, quite properly declares that the tombstone itself is erected to honor the dead. As we feel that we honor our dead more (kibud hamet) by waiting a year, that should be done. It would, however, be within the framework of tradition to erect a stone earlier. Both ways agree with custom and tradition (J.Greenwald, Kol Bo Al Avelut, p. 370). For guidance on a consecration service for the stone, see Gates of Mitzvah (p. 64). As waiting twelve months has become a wide-spread custom among us in America, we should generally wait until that period has elapsed.