I like to idle a little before going, and use a little of the resisitance in the water to help me compress before take off. However, if I wait too long the boat will start moving faster and faster (or the boat has a little faster idle) the ski will start moving around some. Best then to have the driver take out of gear and re-set. Same with the start, I like a slower start but if its too slow the ski in unstable.
"Next skier?"......NEW DRIVER!!!!
I saw a comment about a 3 step start progress, from a driver standpoint..... I'd rather think of it in 1 step. A smooth acceleration to full (or at least close to it, depending on the setup, of course a turn in or island will be different once the skier is on the water.) A slower start takes a little longer to move the throttle to full, a fast start moves throttle to full faster. I think some drivers think of a slow start as moving throttle to a 1/4 possition instead of a 1/2 position (or similar?) I like a smooth acceleration. The trick from boat to boat is feeling out any quirks in the throttle. Our '17 prostar has a spot in the low end of throttle that you really need to feather through or it will be too strong of a start. Driver really needs to use all senses to feel that out for a smooth acceleration (feel and sound of the engine.)
As @MitchellM said, the shorts can make a big difference. I never thought about that till I forgot by swim shorts and tried to ski just in the cargo shorts I was wearing.....holy cow that was no fun. I skied a set, but those start ups wore me out. I missed a couple and wore my back out.... thankfully that was a couple years ago before my back issues were too bad.