Thank you, Itmandella.
There is a wake-up/sleep timer function in the Wiim app that turns the Wiim on and plays whatever music service and playlist you pick.
What I was looking for was something that turns on my receiver, when the Wiim turns on and plays.
With a regular timer, I could have my receiver turned on, and the Wiim at the same time, but that way (as you pointed out), the Wiim probably won‘t automatically stream/play.
What I’m not sure about with the regular outlet timer method, is, if that would bypass the receiver’s built-in delayed power-on function (for protection), and if so, if that’s bad for the receiver.