I was looking at the list of stories and saw that there are quite a few, but I couldn't find a definitive list with all of the stories in proper in-universe chronological order.
So, what is the correct order for all of the stories?
There are some stories for which the actual timing is not clearly spelled out, but the author was kind enough to provide placement for those stories.
There are a couple of minor spoilers in the story Weaver of Dreams but otherwise I think that it, Zuulaman and The Invisible Ring make a good introduction to the main trilogy in that some of the key ideas upon which Blood society is based are introduced and explained. These stories also set up key characters and parts of the overall story of the main trilogy.
"The Time the Witchblood Blooms' (short story) according to an email from Anne Bishop:
(...) probably fits between Daughter of the Blood and Heir to the Shadows. It definitely comes before Queen of the Darkness when Surreal moves to Kaeleer.
In a Facebook discussion, fellow fan Allison King made this comment:
Time the Witchblood Blooms can't take place between Daughter and Heir. The timing doesn't make sense. But it does fit between Part I and Part II of Heir. Certainly before chapter 4, part 9.
It does go between "Kaeleer's Heart" and Tangled Webs. (Surreal mentions dancing with Rainier at a family wedding, meaning at Daemon and Jaenelle's wedding.)
Generally (and this series is no exception), you should read them in publication order. Acording to the dates in the wikipedia entry that order follows: