Marty, read your instruction sheet. it's been a long time, but I think it says to just use the boarder of the instruction sheet to "square" up the first few ribs as the trailing edge is notched. It is often suggested to NOT cut the leading and trailing edges to length, just make a couple of extra ribs and add them to the ends of the wing panels. read you instruction sheet and see if that jives with my memory.
Type at you later,
Dan McEntee