I actually started my roll from the same point as the heavy a/c, not an intermediate point.
Not always the better place to start a takeoff. You will lift off right into the disturbed air from the jet. A PA-38 will never outclimb a jet (or darn near anything else), so you may be safer under the wake of the jet, (though after, by many minutes, is still the most safe). Study videos of wake turbulence, there are many, and begin to imagine where they are found relative the the departure path of the jet - and fly to avoid. In some cases, intersection departures on very long runways have merit in GA planes.
I had a wake encounter in a 150, behind another 150, and it was enough to sharply roll my plane, heavy to light is very much worse!