If what was anounced is right and the First Class is going to be released in 18th July of 2014 then it's officially
728
more days until the film is released.
Since X-Men didn't reach 728 yet let's start with the first appearance of the characters and other notorious stories.
Day 1
Yes, let's start with the classic first one. The First appearance of Magneto, Charles Xavier and Beast (This is just for the characters that appear in the First Class movies).