When I taught this to my old conure, I intended on twirling my index finger to be the cue along with me shouting "spin!" She eventually learned the trick cue as being moving my hand to the right side of her, since I made a little circle around her with a treat starting there.
When I started teaching it to my cockatoo, I taught it the same way, hoping for him to pick up the twirly finger as well, but ended up with him simply doing it to me just saying "spin!"
What does your bird cue to? XD