Q. Do you have to go in the day of the shloishim to visit the kever?

A. Although Shulchan Aruch (Y.D. 344: 20) mentions that one should attend the kever on the day of shloshim, he could be referring only to the exceptional leaders of Klal Yisroel. See however Ma’avar Yavok, Nitey Gavriel (Avelus 2: 37; 3) Mourning in Halacha (p.340) and others that it is customary for all to visit the burial cite.

Horav Shlomo Miller’s Shlit”a opinion is that, this like many of the halochos of avelus, depend on each family’s tradition.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a