Both Tachnun & Hallel come from the same wonderful Sepher of Tehillim:- Pick Chapter 6, or Chapters 113-118.
R.T. According to the Rabonut, your concern has become a thing of the past, because nowadays when Yom ha’Atzmaut is a Tuesday [as was the case last 2 years & next 2 years] they were Madche [delay] Yom haZikoron from Sunday to Monday to reduce Chillul Shabbos, so then Yom ha’Atzmaut gets pushed off to Tuesday.
Sam2:- Do you mean to say that Rav Schachter shlita doesn’t hold of being “Makdim” Yom ha’Atzmaut? He is a huge Godol, so I’ll follow his lead & recite Hallel on Friday Iyyor 5th, akin to what I did 4 years ago, to recite Hallel on Shabbos Iyyor 5th.
Please let me utilize this opportunity, to wish all you readers a wonderful Chag Sameach, on this 64th = 8 squared anniversary.
We shall be back here on this forum,in 23 days time, celebrating 4 & 1/2 decades of the Ness Golui of Yom Yerusholayim. The awesome words “Har haBayis bYodeinu” still ring in my ears to this very day, and literally send chills down my spine, every single time I think of those incredible words & moments.