Usually Shir HaShirim is said on Shabbos Chol Hamoed Pesach. This year where there is no Shabbos Chol Hamoed the Minhag in Chutz L'Aretz is to read it on Shabbos Achron Shel Pesach. In Eretz Yisroel where there is no Shabbos Chol Hamoed Pesach and no Shabbos Achron Shel Pesach, when is it read? Is it read on the first day of Pesach or some other time?
Nit'ei Gavriel (Pesach 108:5) states, as Dan mentioned in his comment, that in Eretz Yisrael in such a case they read it on the first day of Pesach, and in chutz la'aretz they do so on the eighth day.