Status Update (1)
Picked up my Ancient Pandaren Fishing Charm 1 minute before the server shutdown this morning.
Additional Comments by Date (5)
From what I can gather, it looks as though Blizz has "normalized" event times. So this means that instead of server time, it is based on PST. So they will be spawning now at Midnight PST, 3am EST.
Looks like these can be found in the northwestern corner of the of the Valley of the Four Winds. Just got my Rare at 26.6, 51.7 just south of the Singing Marshes.
So, by "facts" you mean "theories."
Common throughout all of Silverpine. There are a bunch in the Battlefront.
If you are having trouble finding one of these, try killing all the Roaches and Maggots you come across.