Well, in the Tale of Years in the Appendices, it says 'passing of the Ringbearers and end of the Third Age.' That's what I've always assumed to be the indicator.
They have 25th March as New Year's Day in Gondor, though, once the Ring is destroyed. Confusing, eh?
...
Finarfin DOES sound like someone who would drink tea, you know.
Fingolfin is more the lager chap, I'd say. Feanor probably had a lethal home-brew of his own making.