I agree with everything here with the exception of priming. It is just unecesarry to do until after the texture goes up.Definitely do your prep work before just texturing. Make sure all the tape joints are good and solid/no loose tape. Float over any scrape marks you may have gotten from your blade. I always float more over all the tape joints and nail heads. They know when they are going to spray acoustic that they don't need to have it finished quite as well as regular textured walls.
*I also like to give the ceiling a bit of a sand down before even beginning any of the floating. It helps to keep from having that stuff dragging in your mud while your floating.
Once you've floated and sanded to the point you think it's ready, prime the entire ceiling and recheck it all. If need be you can touch up the floating some more and prime those areas again.
Then you should be ready for texture.