Roddenberry himself was adamant that Star Trek’s history had to remain a possible history for viewers. So, the dates can slip as long as the major events don’t.
That is why he put WW3 later than implied by TOS, delaying it to the mid 21st century in the TNG pilot ‘Encounter at Farpoint’ even though that led to a contingent of TOS fans insisting that it ‘had to be a separate universe from the one of the original series.’
While writers never explicitly resolved this onscreen during the Berman Era shows, preferring to weasel with offscreen head canon in interviews saying that perhaps the Eugenics Wars were covert and going on unknown in the 90s, the new shows have dealt with this problem head on by acknowledging that temporal incursions do affect the timing of major events without making it a separate timeline.
SNW and Prodigy have been able to make this clear onscreen in canon with the expert help of the franchise’s excellent physicist science advisor Dr. Erin Macdonald. (She did her PhD with the team in Scotland that got the Noble prize just a couple of years later. She’s truly on top of modern theoretical physics.)
I’m not attributing anything here. You’re arguably the one clinging to your head canon.
I’m an older person who was around to hear other OG fans complain about this ‘alternate universe/timeline for TNG’ theory in the late 1980s. And to see how the Great Bird himself responded.
Roddenberry went on the record saying that the timeline had to adjust to always keep the show’s future as a possible future for the audience. He defended the shift in the timing of WW3.
Goldsman, who has been a fan longer than almost any of his detractors, would have heard this more than I did. Goldsman organized one of the very first clubs and fanzines as a preteen, and attended the first ever convention in New York City.