Headliner help

In the process of installing a one-piece plastic headliner in my 73 Sport. Test fit was done w/o the headliner vinyl on it. Went in with both front and rear glass installed. Had to do some minor trimming at the front and rear. The rear was at the corners where it slides under the gasket. The front was about 3/16 all across the edge.
out headliner came with the vinyl already installed..kind of worried that if i trim it. it will cause the headliner to start failing and.plus th vinyl is rapped over the edge if the plastic