They met, as one might expect, in Yavanna's gardens.
Olorin was sitting crosslegged at the base of a tree, Aiwendil perched in its branches Neither of them noticed the other until Aiwendil jumped down, landing neatly on his feet next to Olórin.
"Hello. Do you mind if I sit here?"
Olórin wordlessly shook his head, carefully watching his new companion.
It started with ten and a half minutes of total silence, then turned into a conversation about the book, then progressed further, and from then on the two were fast friends.