With most planes, you don't want to do test glides. You'd get the same result by driving over the plane with your car
The problem is, you usually can't throw the plane with enough force to get it up to flying speed. It needs the thrust from the motor to accelerate it.
It's not such an issue with a glider, though. Many gliders will fly a long way on a good throw. You may want to get yourself a "runner," a friend who can run into the wind carrying the plane, and then simply let go when he/she feels the plane trying to fly out of his/her hands. Once you get the plane trimmed and you're used to flying it, you can start hand-chucking.