Rebuilding a bench seat

Well, I got it apart and going back together so far so good but I am having difficulty stretching the vinyl over the drivers side rear ccorner properly and I dont want to rip the material.

is it normal to wrestle with the vinyl? I think I have to keep compressing the foam and pulling the vinyl untill it stretches over properly. I figure if it rips or the seam lets loose its a fail so Im trying not to get too forceful with it. Its the outside corner where the seat pivots etc so I have to stretch it over then carefully cut th epivot point and where the lact locks on out with a razor blade.