S1-4 are cribbed from this post, with updated discussion.
Feb. 18 - 1966 - Jack's birthday.
March 28, 1979 - Renee's birthday.
Some time in 1987 - Jack and Teri marry. Jack joins Delta in 88? (double-check the minimum age/service requirements)
Nov.-ish 1988 - Kim's birthday.
Early-mid 90s - Jack leaves Delta, joins SWAT, does his Masters. - IIRC Carl mentioned in RP they were working together in Delta in early 1994.
Mid-late 90s - Jack leaves SWAT, joins CTU - double-check that quote from S1 about how long Nina had worked for CTU or with Jack?
March 2, 2004. - Day 1 - Based on the date of the actual California Presidential primary, though later in the season they say it's 2 years to the day of the Drazen mission, which was in April. Oh, writers.
June 10/11, 2005. - Day 2 - This is based on some stuff off the official Fox site for Day 2 and the Palmer White House. 2010 ETA: IIRC that info had to do with a real-life summit that Palmer was supposedly attending.
September 19/20, 2008. - Day 3 - This was chosen by Chase-mun and we all went with it for evil plotting purposes. 2010 ETA: Supported by the 24 wiki, which points out that the first Presidential debates in an election year are usually held in late September, though it places Day 3 on a Thurs/Fri.
April 24th/25th, 2010. - Day 4 - I have no idea how this was chosen and sunrise time indicates it might be closer to March than May but that's what we have it as. 2010 ETA: "18 months after day 3" is more like March, which would fit sunrise time better. Change? (though if so, that gives an even wider range of dates for S5).
Fall 2010 - Carl in Lebanon.
April 7-14, 2013 (approx.) - Day 6. - Palmer says (in 6x01 iirc?) that there have been terrorist attacks in the 11 weeks since he was inaugurated. Apr. 7th is 11 weeks from January 20th, but obviously might not be exact. Note: check whether stupid neighbour kid has a school day.
2014 - Juma is removed from power in Sangala.
Late 2014/ Early 2015? - Jack leaves the U.S. Mainly based on Emerson's question to Jack as to why he left the US, "a year" before he was subpoenaed, but lots of wiggle room in that.
Late 2015/Early 2016 - Jack is subpoenaed. Actual document says April, but unsure whether that's the original date of the subpoena, or an updated version as Jack skipped out on the original.
2016 - Jack in India in early-mid 2016 ("last summer" comment from Redemption, though unsure whether he means N. hemisphere summer or S. hemisphere.
Jan 20, 2017 - Redemption - Inauguration Day is always Jan 20th, and they're wearing winter coats in Washington, so assuming this isn't any different in the 24-verse.
March 27?, 2017 - Day 7. - From Pres. Taylor's comment about it being a "few months" since her son's death, assuming he was killed soon after Redemption because he Might Know Something. 24 wiki says a news broadcast early on puts this 65 days after Redemption, making it March 26th (or 27th, as the 26th will be a Sunday), but there's all *kinds* of fuckery with later dates (see the wiki entry).
In summation: The 24 writers really needed to make a fucking show bible so they could get this shit sorted, but of course that would have been too easy.