Do I say yiskor in first year of avel or not
Hamakom yinachem eschem b’toch shar aveilei tzion v’yerushalayim.
There are different minhagim and many people have the minhag not to say yizkor during the first year year. Among the reasons is that the avel should not remember their departed relative and come to cry on Yom Tov. R’ Moshe held though, that if the avel would like to say it, it is permitted.
The Laws of Aveilus pg. 274