That' what I was afraid of It's like the Odyssey series of books. Each one is a semi squeal and for some reason 3001 changed all the dates from the previous books, it's just stupid!
Which is why I ignore it because it doesn't make sense. All of the events of the series obviously have happened and has impacted the characters for the "perpetual now" to make sense it would mean shifting earlier seasons more and more into the past which, before too long, they take too far back in the past for the series to have been viable as certain technological, political and sociological advancements become less and less likely to have existed back then.
Some 18 years or so have passed since the first season is we go with the "perpetual now" idea then the first season took place in 1994. Which makes some of the stuff in it slightly less likely. (Not impossible, necessarily just less likely.)
Figuring it out just now it should be sometime in 2019 in the 24 universe assuming the first season took place in 2000, an election year in the past when the show premiered. If it took place in then then future of 2004 then it's 2023 in the 24-universe. Just over 18 years have passed over the course of the series.
Actually, it's an alternate universe. Elections take place 1998, 2002 (The Democratic Primary), etc.
The real question is -- how old is Jack? He's been a grandpa for like 6 or 7 years...how old was he & Kim when they started?
Also -- where's Chloe's child? Or will we find out later?
And Also -- where's Aaron Pierce??? He's retired, so we can't he be in London for vacation?