my gaps are shit atm, but im sure i take off just behind the edge, although i might be wrong completely hahah. i dont pay much attention i just go for it, i turn my body nearly 45* and sort of lean down the side of the wheel when pre-loading. IMO the gapping and the distance u make is down to pre-load, the further u can preload and then spring forward the more power you should essentially get through your bike and ur gap should be further. i think closer to the edge is better, im not sure if i pinch gap, ill have a look at it on camera for you sometime and let you know i probably do