Boruch Hu U'Voruch Sh'mou

Upon hearing someone making a brocho "Boruch Atoh HaShem Eloukaynu Melech ho-Oulom...", does one recite Boruch Hu U'Voruch Sh'mou after the word HaShem (as in the case with other "shorter" brochous), or does one wait to answer until after the word Ho-Oulom, which completes HaShem's title and praise? [Examples: Brochous in the morning, Hallel, Nayrous Chanukoh, Mikroh Megilloh etc.] My father and others I have spoken to, seem to think that it is more appropraite to follow the later opinion.

Rallis