Photo: Pranchiyettan / Wikimedia Commons, CC BY-SA 3.0Go early on a clear day for the viewpoint. The road becomes difficult in heavy rain, and the area can be fogged in. On Kaveri Sankramana (mid-October; confirm the year's Theerthodbhava date and time), the crowd for the Theerthodbhava is huge, so avoid that day unless you came for the ritual. Dress modestly.
Talakaveri, at about 1,276 m, is traditionally considered the source of the River Kaveri. A tank (kundike) marks the spot, with a small temple. Wikipedia notes there is no permanent visible flow from here to the river except during the monsoon rains. It is about 48 km from Madikeri.