According to some people here yes, but let me remind you prerotation is not something recognized by the ISU nor do these users understand jump mechanics whatsoever, and most likely have never stopped a foot on the ice or learned how to jump. Prerotation does not exist under the judging system and I dont understand why so many people like to scrutinize and nit pick these jumps to the point where it makes the sport so much less enjoyable. It's pointless because all this arguing about "correct technique" are opinions and nothing more.
The following was posted by gkelly:
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From the ISU Technical Panel Handbook:
Cheated take-off
A clear forward (backward for Axel type jump) take off will be considered as a downgraded jump. The toe loop is the most commonly cheated on take-off jump.
The Technical Panel may only watch the replay in regular speed to determine the cheat and downgrade on the take off (more often in combinations or sequences).
Toe loops are really the only jumps we see get < or << calls for incorrect takeoffs. Note that the panel is not allowed to use slow motion to determine prerotation.
Judges are required to give negative GOE if the element has a << symbol. (The reduction for << is -2 to -3; if there are other positive aspects of the element, the final GOE might be -1)
Judges are also supposed to take off -1 to -2 for jumps with < calls and for "Poor take-off" but the final GOE does not need to be negative
For triple and quadruple jumps, it's normal for the rotation to start before the skate has entirely left the ice. As long as the blade is still on a backward edge (or forward edge for axels) at takeoff, there's no penalty. But the quality would be considered.
If the upper body prerotates more than the blade and lower body, that's just a the way some skaters do the jump. Only the blade would be scrutinized.
There could be a reward in positive GOE for delayed rotation if the blade leaves the ice completely while still on the same size curve as the entry edge, before the tight rotation starts.