How long have you been in this darkness before you awoke?

Either just wait and see if a dream scene forms, or a thing I like to do is start imagining some sort of dream scene and just start thinking what it would be like and what you would do, and after a while if you arent in it, try to open your eyes and be in it.

Once when this happened to me, I imagined like a opening sequence(like at the begining of tv show where it shows the actors and some credits and stuff) and when it was over I was in the show