Heres a rough sketch of what im talking about...
<Standing up>
<Incorrect transition to butterfly>
<Correct Transition to butterfly>
...
By doing this, not only will you shave of a good second on your reaction time .. but it will put more of the effort you put into driving your knees down, into actually driving your knees down .. and not into any forward movement before your knees start their travel downwards. Also remember to keep you butt out, so that you can use that thrusting motion that comes from bringing it back in to drive your knees down (incase you didn't know that part).
.. hope that helps