Jai Sri Ram.
Excellent thinking. As a Tamil Iyengar following Sri Vaisnavam of SriSri Ramanujacharya, I do appreciate your decision to have Thirunamam and am sure that you are doing so because of some poorvajanma punya & Sri Vishnu anugraham only. Good, you have started thinking about the ultimate truth of very existence of yourself, the great Lord Vishnu. Lord Narayana bless you in fulfilling your desires and guide you on a divine path.
In your endeavour to follow Vaishnavam, I feel you should know and I have to briefly explain you what the Vaishnavam is?
'Om Namo Narayana' is the moola divya mantram for any Vaishnava, and Iyengars are Vaishnavas. Hope, you know something about the most revered and maiden socio-democratic vedicacharya in the history of Indian philosophies is SriSri Ramanujacharya besides his universally accetable doctrines without any birth prejudice & divine preachings on and of Sri Vaishnavism in a lucid language for general mass. He & his followers propagated that "whosoever is wholeheartedly decided to keep him self pure by acharam & vicharam of Sri Vaishnavism, surrrender himself totally to the Sri-pada-pankajam of lord Vishnu with Thayar Sri Lakshmi can become Vaishnava, irrespective of his present existence (varnaa)". One who recites with total sanctity the mantra "Om Namo Narayana" and keep his own consciousness pure with total devotion to Lord Vishnu is a Vaishnav and being a Vaishnav he should mandatorily have Narayana Padam with Sri Lakshmi as Namam ( - Thiruman & Srichurnam) on his forehead atleast. There are many in Tamilnadu & other places, who are Vaishnava with Thiru-namam but do not have the Iyengar lineage but follow Sri Ramanujacharya Swamigal. Welcome to become his true follower.
Regarding sacred-thread, called as Yagyopavitam in Samskrutam and Poonal in Tamil, one cannot or should not buy it in any market and just wear it on one's body. The poonal is not merely a thread but has a lot of spiritual significance. Vaidika-achara-anustanam are to be rigidly followed every day and abide by the Vedic rituals. The Brahma-upadesam is a divine ceremony where the boy is sanctified with homams, mantras, etc and blessed by Acharyas to have the sacred thread. Thus, the boy becomes a sanctified Brahmacharya from a child and becomes eligible for performing certain Vedic pujas and reciting Vedamantras.
So, if you are truly interested to follow the rigid but really pleasing lifestyle of a Vaishnava, please contact a Vaishnava mutt acharya and seek their suggestions and guidance. After accepting the blessings of any Vaishnava or other Acharyas, like great Shankaracharya Swamigal, if you commit anything against the stipulated preachings & Sabatana dharma-neetis, the sin will affect not only you but because of you committing the anacharam and sin, the divine acharya soul too shall feel bad, which is the greatest sin. So, think twice and do what you can really do and follow in life ahead but never deceive your self nor any vedicacharyas of any Parampara & philosophy, who has blessed you. All Vedic Acharyas of all the mutts are actually the living incarnations of Lord Vishnu & Lord Shiva and they are the attained souls, living in this lokam for guiding us properly for Dharma paripalanam & salvation finally. Start doing manasikarupena Sastanga namaskarams to all the great Acharyas or any one Acharya (though all philosophies are like different rivers, their ultimate goal or final destination is ocean only- the Paramam) every morning and automatically, you will be guided by the divine positive energy in cosmos to reach them when your punya-kalam comes as per your Poorva karma and destiny. You may even try yourself to communicate in this regard with any Vaidika mutt of Vaishnavam. सर्वे भवन्तु सुखिन:। शुभं भूयात्!
