Which blessing is said first-Shehechiyanu or the blessing over the fruit?
One who eats a new fruit which requires the recital of Shehechiyanu, is to first say the blessing of Shehechiyanu and only afterwards recite the blessing of Haeitz or Hadama. [However, if one forgot and first said the blessing of Haeitz or Hadama, then he may recite Shehechiyanu afterword’s, prior to eating the fruit. The above ruling is only regarding the blessing of Shehechiyanu said prior to a new fruit, however, when saying Shehechiyanu over a Mitzvah, one first says the blessing over the Mitzvah [i.e. Asher Kidishanu], and only then says the blessing of Shehechiyanu. The above follows the ruling of Admur and other Poskim, although the widespread custom of many is to always recite the blessing over the fruit and only afterwards to say Shehechiyanu.]
 Seder Birchas Hanehnin 11:12; Yosef Ometz [Minhagim] 422; P”M 225 A”A 7; Conclusion of Mamar Mordechai 225:1; Kesones Yosef 225:18; Ashel Avraham Butchach 225; Chayeh Adam 62:8; Shulchan Hatahor 225:6; Aruch Hashulchan 225:5; Custom of Rav Nasan Adler and Chasam Sofer, brought in gloss on 225; Kesav Sofer 25; Daas Sofer 1:26; Kitzur SHU”A 59:14; M”B 225:11 in name of P”M ibid; Ketzos Hashulchan 63:1; See also regarding saying Shehechiyanu on a Tallis Gadol, that it is said prior to the blessing of Asher Kidishanu: Admur 22:1; Olas Tamid 22:2; Beir Heiytiv 22:2; See Piskeiy Teshuvos 225:12 for different customs and Poskim regarding this matter.
Other Poskim: Some Poskim rule one is to first say Haeitz and then Shehechiyanu and so is the custom of many. [Halachos Ketanos 1:236; Beir Heiytiv 225:6 in name of Halachos Ketanos; Glosses on Tur 225; Mamar Mordechai ibid that so is custom, although he himself concludes differently; Chida in Yosef Ometz 56; Machazik Bracha 22:3; Peri Hadama 1 Brachos 10; Yifei Laleiv 225:4; Maaseh Rav 21; Siddur Derech Hachaim; Ashel Avraham Butchach 600; Gloss of Chasam Sofer 225, even though he was accustomed differently; Avnei Nezer 450; Sdei Chemed Brachos 2:5; Aruch Hashulchan ibid that so is custom, although he concludes differently; Birchas Habayis 24:4; Kaf Hachaim 225:24 that so is the custom; Yechaveh Daas 3:15] See also regarding saying Shehechiyanu on a Tallis Gadol, that it is said after the blessing of Asher Kidishanu: Birkeiy Yosef 22:2 based on Elya Raba and Michaber; Machazik Bracha 22:3; Siddur Beis Oved 23; Shaareiy Teshuvah 22:2; Chesed Lealafim; Kitzur SHU”a 59:8; Kaf Hachaim [Falagi] 10:8; Ben Ish Chaiy Bereishis 7; Ashel Avraham Butchach 225; M”B 22:3; Kaf Hachaim 22:7; See Kaf Hachaim ibid that argues on the Beir Heiytiv who claims the Bach held of the opinion of the Olas Tamid. The reason behind this opinion is because they view Shehechiyanu as an obligatory blessing [see Yosef Ometz ibid] and thus we apply the rule of Tadir and Eino Tadir, Tadir Kodem.
Sefaradi Custom: The Sefaradi custom is to first recite the blessing of the fruit and only then Shehechiyanu. [See Sefaradi Poskim ibid who make this statement]
 The reason: Some say the reason one is to precede the blessing of Shehechiyanu is because the blessing of Shehechiyanu is ideally said over the joy of seeing the fruit, and it just happens to be that the custom today is to approximate the blessing to the eating. Thus, one is to first say Shehechiyanu and only then the blessing over the fruit. [P”M ibid] Others however explain that the blessing of Shehechiyanu and Hatov Vehameitiv was established over the joy of having the fruit, while the blessing of Haietz/Hadama was established to be said only when one actually eats the fruit. Thus, one is to first say Shehechiyanu on the joy and only then the blessing over the fruit. Accordingly, if one says the blessing of Shehechiyanu after the blessing of Haietz/Hadama, but before the eating, it would constitute a Hefsek between the blessing and the eating. [Glosses on Seder by Rav Alyashvili] Alternatively, since the blessing of Shehechiyanu is voluntary, and is hence not appropriate to be said between the main blessing and eating. [Shaar Hatziyon 225]
 P”M 225 A”A 7; M”B 225:11; Ketzos Hashulchan 63 footnote 5; Likkutei Maharich
 Admur 643:1
The reason: As the blessing of Shehechiyanu over a Mitzvah was established to be recited only at the time of the Mitzvah.
 See other opinions in previous footnote who testify that so is the custom of the world, even though some of these Poskim conclude differently.