The minhag to recite the nesi’im during Nissan is the minhag of my shul. It is expressly written in Tukochinsky’s famous Luach Minhagei Eretz Yisrael and is practiced by most if not all Ashkenazic shuls in Israel. It corresponds to the dates that the nesi’im brought their sacrifices after the Mishkan was built, after Shivat Y’mei Ha’miluim.
Please don’t compare it to shlissel challah.
Kudos to the person who had the guts to introduce a custom to a shul filled with well meaning but poorly educated mispallelim.