Amazing Spider-Man Annual (1964) #1 (1st story)

Cover by Steve Ditko

Cover Date: 1964

On-Sale Date: June 1964

Synopsis: Spider-Man has to fight six of his strongest villains to save Aunt May and Betty Brant. Meanwhile, the X-Men ignore his plight to continue training in the Danger Room.

CHRONOLOGICAL NOTES:

The X-Men make a one-panel cameo in this story, in a shameless bit of salesmanship.  Iceman is still in his snowman form, and Professor X is present, so this story most likely takes place before X-Men (1963) #7.  (It could also be after X-Men #9, when Xavier returns, but I'd prefer to keep it closer to its publication date.)  Also note that Marvel Girl's cowl has returned to its original design. She'll try one more style out before giving up on it for the time being.

Later in the story, Mysterio will use robot versions of Angel, Beast and Cyclops to attack Spider-Man. This isn't all that relevant to X-Men continuity, though.

Finally, pretty much every Marvel hero with their own title makes a cameo in this story: Thor, Dr. Strange, the Fantastic Four, Giant-Man and the Wasp, and Captain America (who doesn't have a book, but is here to promote Avengers).  Human Torch also gets featured to promote his solo strip in Strange Tales. This is pretty much the full slate of active heroes at this time, except for the Hulk (whose book was cancelled at this point).

COUNTING THE DAYS

From the perspective of the X-Men, this story takes place in a single day. Peter Parker gets hassled by Flash Thompson for walking Liz Allan home from school "the other day", so it must take place during the school year.