the one thing that helped me out was thinking about the 360 aspect of the trick without thinking about the tantrum. it was all mental for me. if you dont think about the tantrum, do it subconsciensly, and focus on not rotating too early you should be ok.
that probably doesnt make sense to you, but i tried.
BS 3s took me a while to nail consistantly. tantrums only a couple days. and never let you arms get all the way out.