In general, isn't it preferable to apply power first rather than using up runway and losing valuable momentum while fiddling around with flap and so on?
In my book a touch and go is the same as a go-around and the same procedures should be followed: power first then flap retracted to take-off setting. If the student can't handle the aircraft during this phase of flight, then they might be better off with stop-start circuits until they are fully comfortable with go-around procedures.
Despegue:- On a specific point, 10° flap is not a recommended position for take-off in the P28R: either zero or 25° are your choices! Vr is 55kts for 25° flap, and 65kts for normal take-off.