IFa beginner was to follow the texbook he would assume that you would use the same amount of energy from each foot to dance the rise in a NT,but we know that good dancers use body swing to dance the rise and fall to the rhyme of the music so it is perhaps posable to swing up onto that left foot without using it for anything more than to change weight. As for timing we are told to dance a long beat two and Johnathen has said in the past that he takes longer than half a beat to change shape and lower, also it seems that many good dancers reach the top on beat two of the music?