Who's the oldest?

[*Varda*]

I always had the impression that the Ents and the Elves were the same age.

When the children awake, the thought of Yavanna will awake also

Silmarillion, of Aule and Yavanna

Manwe was speaking to Yavanna of the Ents, the tree shepherds. Yavanna was worried no one would look after the trees, and so the Ents would awake when the elves awoke at Cuivienen. That's what I think anyway.

I'm still not sure about Tom though. Perhaps we'll never know.