I thought it might be appropriate to start an ongoing discussion thread specificially devoted to issues related to the in-universe X-Men film timeline (i.e. - making this THE place on the wiki to discuss any timeline-related issues).
As a starting point, I'd like to state what I think should stay the same or should be changed on the timeline. Of course, this is all open to interpretation, and if anyone feels that a date listed here should, for instance, change rather than stay the same (or vice-versa), let's talk; after all, this is a discussion thread! ^^
Dates (and events within them) that I think should stay the same:
Pre-3600 B.C.; 3600 B.C.; 1845; 1859; 1861-1865; 1866; 1900; 1909; 1915; 1917-1918; 1927; 1941; 1944; 1949; 1953; 1959; 1961; 1962; 1963; 1964; 1967; 1968; 1971; 1973; 1976; 1977; 1980; 1982; 1983; 1986; 1988; 1989; 1991; 1994; 1996; 2001; 2005; 2006; 2008; 2009; 2010; 2011; 2012; 2013; 2014; 2016; 2018; 2023; 2026; 2028; 2029
However, of these dates, I feel that the following need endnotes for events:
1961; 1962; 1963; 1964; 1967; 1968; 1971; 1973; 1976; 1977; 1980; 1982; 1983; 1986; 1994; 2010 (Original Timeline); 2016 (Revised Timeline); 2018 (Original Timeline); 2023
Additionally, the events for the following dates should have the endnote "Historical Fact", as they are relevant to the history of genetics, mutation, and evolution, and compliment issues and ideas discussed in the films. If there's any relevant historical fact/event related to any of the previous listed fields that compliments anything said in the films that someone would like to add, please suggest it here and it will be taken into consideration:
1859; 1866; 1869; 1900; 1909; 1915; 1927; 1941; 1944; 1953
Now, here are the dates (and events within them) that I think should be either changed or at least thoroughly discussed as to why they should change or stay the same:
1832; 1930; 1932; 1934; 1955; 1970; 1974 (Original Timeline); 1979; 2003
As a starting point, I'll give reasons why I think the preceding dates should be discussed:
1832 - Has it been canonically stated anywhere that James Howlett's birthdate is this year? While its safe to assume he's in his early teens in the flashback scene in Origins (in 1845), is there any reference to a specific date?
1930 - Has it been canonically stated anywhere that Erik Lehnsherr's birthdate is this year? While its safe to assume that he was born in the 1930s based on the flashback scenes in X-Men and X-Men: First Class, is there any reference to a specific date?
1932 - Has it been canonically stated anywhere that Charles Xavier's birthdate is this year? While its safe to assume that he was born in the 1930s based on the flashback scene in X-Men: First Class and Logan (the latter which takes place in 2029 and where he states he's a nonagerian - someone in their 90s) is there any reference to a specific date?
1934 - Has it been canonically stated anywhere that Raven Darkholme's birthdate is this year? While its safe to assume that she was born in the 1930s based on the flashback scene in X-Men: First Class, is there any reference to a specific date?
1955 - I don't think its totally relevant to state the Vietnam War's starting date, as no other starting date for any other real-world war is given in the timeline.
1970 - Where was it stated that Charles became addicted to the drug this year? Maybe it was in the film (or Rogue Cut), and I completely missed it. :-P
1974 & 1979 - As a history buff, I take slight umbrage with the notion that Logan and Victor were fighting in Vietnam with regular American troops in 1974 (as it has been placed on the current version of the Timeline) - a year after American military participation in any form ended (in both the real world and in the film universe) by the 1973 Paris Peace Accords). I highlighted some of these issues in my blog post:
However, I am now more open to the idea that Origins might be set sometime in the 1980s (in the Original Timeline, of course), as it has pointed out that there are several inconsistencies which more or less preclude it from being set (for the most part) in 1979, despite the presense of Three Mile Island.
Also, in the Revised Timeline for 1974, it states that Xavier reopened his school. Again, is there a reference anywhere for this?
2003 - There's has always been a debate as to whether the first two X-Men films take place either in 2000 or 2003. I think it's worth some discussion.
Finally, if there's anything that I didn't mention here that anyone thinks is worth discussion, please feel to free to mention it.