I usually try to get my characters to experience the first dream
in order to unlock a part of Astarion's backstory early on
.

I have been using the tadpole willy-nilly on my post Patch 3 playthrough.
The latest instance when I used it was on the gnoll warlord
But I am yet to have the first dream, even though I am almost finished with what is available during Early Access!

Astarion still shared his backstory through other cutscenes
but this is still very odd.