Well I started in Ul'dah and did the first opening 'mission' (I'll just call it that for now) which gives you the Gil, guides you through emotes, etc.
I'm not sure WHEN this became available - but I know people have been like "nothing new blahblah" - but I am Physical8, Alchemist8, Botanist4 and Thaumaturge1 - and when speaking to Monodi in The Quicksand she had something new called "Golden Sacrifices" available - which I started.
I'm not going to continue it until my wifey is ready - she's a little behind me so I will have her see if can she pick it up at a lower level or not. If she can - I will report back with her Rank - if not - I'll let you know.
I'd assume the continuations of each quest/mission is available in each starting city.