वैष्णवाचमनम्

In the आचमन routine, following names of विष्णु are invoked

केशव नारायण माधव गोविन्द विष्णु मधुसूदन
त्रिविक्रम वामन श्रीधर हृषीकेश पद्मनाभ दामोदर

When do they first occur in literature?

They are found in the viShNu-bAlI/viShNvarchana mantra of a number kR^iShNayajurvedic gR^ihyaparishiShTha-s: vaikhAnasa, agniveshya and baudhAyana. This suggests that it emerged in a branch of “para”-taittirIyaka-s who were also early sectarian vaiShNava-s. I say “para” because there is evidence that the vaikhAnasa-s had a now lost brAhmaNa distinct from the other taittirIyaka-s.

Also see R^igvidhAna 3.27.139 onward: keshavam mArgashIrShe tu pauShe nArAyaNam… also from the same temporal layer but from the vaiShNava-s of the RV tradition.