Excellent aegument. Since the white horse came during the Churning of the ocean, - in fact Moon, Indra himself and Mahalakshmi all came during the churning only - and - Dhanvantri dyana sloka mentons Amruta Kalasa Hastaya .
But The Kumbhamela story is equally popular.
Can you please check whether the person carrying the pot in Govindaputhur is Danvantri or Garuda?
The face looks like Garuda. Can you pl enlarge and check.
Isn't the white horse which came out was Ashvaishrava who was taken by Indra as his second mount? I assume that the horse is usually shown with one horn, like Unicorn, however I am not very sure, will try to find out more on this. Garuda taking kalasha from Dhanvantari is new to me, was not aware of this before.
Mohini with Amruta Kalash - Vaikundaperumal temple, Kanchipuram In the following version, Vishnu himself is running for 12 days ( human years) http://en.wikipedia.org/wiki/Kumbh_Mela Can any one enlarge the Govindaputhur panel and find whether that is Garuda or Danvantri