Parashath Bereshith, Laws of Ziziyoth, Page 6
7. When one puts on a new tallith for the first time, one should recite the berachah 'shehehyanu after the berachah 'lehith'attef.' It is not customary to recite 'she-heheyanu' over a new tallith qatan, because a tallith qatan is not usually made of material of such good quality that the wearer would derive any special pleasure when he puts it on for the first time (cf. parashath Re'eh, 1-4). If, however, one did make the tallith qatan from an expensive or good quality material, and one did experience some pleasure when first wearing it, one should recite the berachah 'shehehyanu.'
This learning should be in memory of Maran, HaRav HaGaon Ovadia Yosef, ztz'l.