Starting out

This is obviously from a newbe. I will be driving the boat for some very new wakeboarders. They have had some lessons and can at least get up on the board. The question is: how fast and hard do I pull them up? Do I just throw the throttle wide open from a stopped position and ease off when we get up to around 20MPH? Or is there a more subtle and skilled approach? This is from the driver of the boat. Wishing that I had gone along on the lessons to observe.