There are various opinions among poskim about when to make the brachah of “L’hisateif be’tzitzis” on a talis gadol, but the common practice—which is also the Chabad custom—is as follows: 1) One places the folded talis over the right shoulder and examines the tzitzis while saying Borchi nafshi. 2) Then he unfolds the talis and begins saying the brachah as he holds up the open talis behind him. 3) He then rests the talis on his head and shoulders with the front edge of the talis covering his eyes and gathers the two right corners of the talis in his right hand and the two left corners in his left hand and raises them up, bringing his right hand up to the top of his left shoulder. 4) He then finishes making the brachah and immediately brings the two right corners in his right hand over his left shoulder and around to the back of his neck. 5) He then recites Ma yakar while draped in the talis. However, if one did not make the brachah as described above, he can still make the brachah as long as he is wearing the talis, since the mitzvah of l’hisateif be’tzitzis continues as long as he is wearing the talis. In this instance, he should first touch the tzitzis before reciting the brachah.