I came here to post my guess about when what's his name first heard about the Skrulls....

and the thread's been locked? Anyway my guess is Marvel's Greatest Comics #72 from 1977 which is a reprint of Fantastic Four #90 from 1969. This seems to be a 4 comic story arc which continues in FF #s 91, 92 and 93, all of which came out in 1969 and were also reprinted in MGC #s 73, 74 and 75.