Matting is harder than I thought

I bought 12 frames for the photography show, starting next week, that my pictures will be in. I thought I was clever and bought nice wood frames with a wood matting already inside. Woe is me, though. My 8X10's are exactly the size of the hole and lining it up without showing the white strip around the edge of each photo is near impossible.

I've got 5 hours to fool with 11 more and git um straight. We'll see.