No, not quite what you're thinking. . . . . . FRAMING. What a learning experience. I've built the Same wall 3 times over and finally got it right. The number one thing I've learned: if the area your framing on isn't level all hell breaks loose. End rant.
They say it's better to just walk away for a few minutes from a job that's just not going right, for some reason or other. That may be true, but I say it's far more satisfying to just beat the ***** out of it with a hammer.
If you attach the top plate with IB3 clips leaving the wall decoupled you have a pretty large margin for error. Measure the wall in several locations, subtract one inch from the smallest measurement, cut your studs all at the same length, build the wall and tip it up.
The picture looks little like an m. c. escher drawing. Look at the bushing. There is the space for the bushing below the horizontal portion of the clip, then the clip bends. Look closely and you'll see the bend in the clip is just below the bottom edge of the joist.
So your top plate should be about 1" from the joists? That picture makes it look like they are touching.
1/2 is fine but when you try to make it too close you often miss your mark. If you are decoupling the wall that means you will be using clips and channel on the ceiling and the drywall will be hanging down starting at 1 inch below the joists.