I don't know about you guys, but I get the dream after the very first time I use the tadpole to compel or dominate (using it on/with/against your companions doesn't seem to count, and in most cases I never did anyway). One (Authority) use, warning about tadpole taking something you'll never get back, then dream at first rest after that. Then, almost immediately, one more (Authority) use, and right away, second dream on the next rest.