My son seems eager and ready to put on Tzitzis (2.6 years old), does he make Shehecheyanu?
No, because the Bracha of Shehechiyanu for Tzitzis is for the clothing of it, not the Mitzva, and a Tzitzis is not (generally) considered an important garment in this regard.
You can buy him a new fruit and he will say Shehechiyanu on both.
Sources:
ראה שו”ע או”ח סימן כב ובמג”א שם. ובנוגע לט״ק בפרט – בא״ח ש״א בראשית ז. לקו”ש חי”א ע’ 289 בענין הדלקת נש”ק ותפילין. כפר חב”ד גליון 500 ע’ 18. התקשרות גל׳ תרכט ע׳ 13, נעתק בשלחן מנחם או״ח א קכט. ולהעיר מסדבה”נ יב, ה.
#9770
Doesn’t it say in sefer minhagim and in Hayom Yom that we don’t make Shehechiyanu even on Shabbos in the 3 weeks?
Although this question was just posted on our website, it is not addressing the 3 weeks (see the categories and tags), in which, indeed, we don’t make Shehechiyanu.