Why is there an unveiling of the gravestone on the year anniversary of a death? Why wait a year?

There are varying customs regarding the time of unveiling. Some erect the stone (at least in unfinished form) immediately after the shivah (first seven days of mourning after burial) and they make sure to complete it by the Shloshim (30 days after the burial).

Most people, as you mentioned, wait a year before erecting the gravestone. I’ve heard two reasons which might explain this custom:

1) The monument is a sign of importance and thus inappropriate during the first 12 months while the deceased is suffering (According to Jewish tradition, each soul is judged immediately after death and undergoes the appropriate purification process in Gehinnom – the Jewish version of Hell. For the majority of those who need purification that goes on for a maximum of 12 months).

2) The purpose of the monument is to make sure that the person will not be forgotten, and this is not necessary during the first 12 months while the memory of the deceased is still fresh in peoples’ minds.

Sincerely,
Rabbi Ari Lobel