Do the cheap leg stretchers work as well as the expensive, and how long will it take to do a split,?

Im15, Me and my sister have competitions and i just want to do a split, but how long will it take for me to do a split, and do the leg stretcher without the handle in the middle work as gret as the one in the middle? & the most im wondering does it hurt? Also i would like to add how long should i stretch, and how many times per week, and will the one without the handle in the middle , will i be able to do splits?