The only time I've waited for Fates specifically was during atma books, and I got REALLY lucky since all but five of them spawned almost immediatly when I got there. Two of them I waited fourty minutes on (One in Outer La that escapes me, the other being Seps.)

Technically I had to wait on the four Ixal bird one for over 8 hours, but that was because of Maint/getting out of a dungeon and just BARELY failing because of a time out.