Irvin, TBH I don't think the 10% pre-stretch is needed. I'd prefer to stick to a few pound more so that those strings are set at a constant tension.
With squash stringing one tends to use low tensions, around 22-28lbs. 10% would make little impact as you'd only be adding on ~2lbs before settling back at the usual tension.
Babolat Strike 18 x 20; Wimbledon stringing team since '04 - Head Wimbledon stringer '14; Babolat stringing team '10-'14. Twitter - @therqtstringer