For goodness sake, do it by the book!
For what its worth, here is what my Piper Arrow manual says:
"Short field takeoff with an obstaccle or soft field differs slightly........Flaps should be lowered to 25 degrees (second notch)....allow the aircraft to accelerate to 50 to 60 knots depending on aircraft weight and rotate to climb attitude. After breaking ground accelerate to 55 to 65 knots and select gear up. Continue accelrating etc etc.
As for landing, all they say is for short field is full flap and enough power to maintain approach speed (75 knots). Reduce speed during the flareout and contact the ground close to the stalling speed (55 knots). It then goes on to talk about holding the nose wheel off, putting weight on the mains and raising flaps. It then cautions about using partial or no flaps in high wind or crosswind conditions.
From memory the Warrior manual says much the same thing, except I can't remember if you use flaps at all.
Please be very very cautious about instructors who show you a "special" technique unless they are old and very experienced and can explain in detail how and why the procedure works.
Remember that most training is done at well below max weight and what works when your instructor demonstrates it may not work so well when you have Mum and the two kids on board.
Please note that in a Cessna 210 (laminar flow wing) if you rotate too early you will simply traverse the entire length of the airstrip before hitting the fence.
There are a few other interesting ways to get killed, like getting a little too slow on approach and falling out of the back of the drag curve.
As for applying flap during the takeoff roll, you are asking for trouble. One day you will either forget because you are dealing with some other problem, or something will occur just as you reach down for the switch or the bar. I've already nearly been killed by a sticky Cessna flap switch and I don't take my eyes off the runway just to check if the flaps are extending. Things can happen very fast and you don't need to add unnecessarily to your own workload pulling this trick. The gravel strips I've used require all your attention just to keep the aircraft pointing in the right direction and on "centreline"
For goodness sake, use the book!