Security screws seem to have been used starting in early 1988.
I recall that from reading a document years ago comparing games made in both three and five screw variants, and it seemed to point towards early 1988 (games more common in five screw were generally older games than that, while those more common in three screw were comparatively newer games). Though three screw flathead carts DO exist, I'm sure I have one of them somewhere.
Late 1987 would seem like the right time for such a cart to exist.
I had a feeling and I was able to quickly locate it to verify that my Kid Icarus IS a flathead three-screw which would probably match up timewise.