back foot in butthole, handle by your front toes with arms straight. Ski pointed slightly left if a lefty, right if a rightie.
Have driver drag you about 5 feet to start your motion going forward, then gently roll up. When I used to start double booted as a big guy, I preferred a slight bit of forward momentum before holeshot so you're not digging out from a dead stop. If you watch any tournaments, you'll see this is how everyone starts.
There's a misconception with big skiers that we need WOT holeshots. While it's true that on some boats we might get up to WOT, it shouldn't be before the skier is already out of the water and starting to extend their feet away. WOT with a guy plowing water is a good way to need a new mirror for your boat, or worse.
On the ski though, what's the Vapor doing for you that the Senate doesn't? I skied a Vapor for several years before switching to the Senate, and I haven't looked back.