According to 'Hindu Samaskaras' by Rajbali Pandey, the samaskaras of
1. Jatakarma (Birth Ceremony)
2. Namakarana (Name-Giving)
3. Nishkramana (First Outing)
4. Anna-Prashana (First Feeding)
5. Chuda Karana (Mundan or Tonsure)
6. Karnavedha (Boring the ears)
Jatakarma was performed before the severing of the navel chord. This can change because of other factors like death in the family etc.
Namkarna is performed on tenth or twelth day after birth. There is again a wide option for the dates.
According to Pundit Prem Nath Shastri's Juntree, Jatakarma is Kahnethar. But it appears to me that the present day ceremony includes portions of both Jatakarma as well as Namakarna.Each Rashi contain two and a half Nakhshatras. That is why when you go to a South Indian Temple, the priest wants to know your name, Gotra, and Nakshatra. This is more precise than Name, Gotra, and Rashi. Most of us know our Rashis but have no clue about the Nakhshatra. Ask your priest. This side discussion apart, the naming has a lot to do with the nakhshatra (Nakhetur in koshur). As was pointed out by Subhash Ji, Kahnethar is but a deformation of the word that implies the naming ceremony done on the eleventh day after birth.
I must again point out that ALL samaskaras among
ALL Hindus are performed according to Greha Sutras. The details of Homas
(havan), naming convention for Namkarna etc, are standard. The details vary
according to the local traditions. For example, Kashmiris use Tantric symbols
that are absent in all of South India. Kashmiris chant vedas in Sama (singing)
style, whereas South Indians chant in very crisp measured style. The stuff they
chant is exactly the same. The Dhrivyas (items for worship) are also local
stuff. Naturally we use things we are used to, like walnuts and almonds, and
Nabad (nabaat of persians). South Indians use coconut, palm leaves, etc. So, if
you want to do any of these ceremonies here, go find a knowlegeable South Indian
priest, tell him a few things about your own customs, and enjoy a genuine
function. DO NOT ask them to use tantric signs they are taught to stay away from