From the Bhakti List Archives
Mani Varadarajan
• Fri Jun 18 1999 - 13:01:06 PDT
I found out the answer to the upAkarma question asked
earlier. The dosha is only for prathama (first-time) upAkarmins
of Rg and Yajur Veda. Others can perform the upAkarma on
their regular date, viz., August 25 for Rg, August 26
for Yajur, and September 12 for Sama.
This topic was discussed by Sri Sadagopan in a previous year:
http://www.ramanuja.org/sv/bhakti/archives/aug98/0055.html
Mani
P.S. Why is it no panchAngam lists atharvaNa upAkarma?