Are you confused by all the alternate timelines in the Terminator franchise? So are we. That's why we created a list of every timeline, and ran it past Sarah Connor Chronicles producer Josh Friedman. Spoilers...
1) The original (?) timeline: Sarah Connor conceives John Connor with some random guy. (All we hear about him is that "He dies, even before the war." Presumably it's not Kyle Reese, since time-travel always seems to create an alternate timeline.) John Connor's resistance is on the verge of defeating Skynet in 2029. (Reese says, "The defensive grid was smashed. We'd taken the mainframes. We'd won. Taking out Connor then would make no difference. Skynet had to wipe out his entire existence." Date of Judgment Day: August 29, 1997.
2) A T-800 and Kyle Reese both travel back in time from 2029. Kyle Reese fathers John Connor. Date of Judgment Day: still August 29, 1997.
3) A "scrubbed" T-800 and an "experimental prototype" T-1000 travel back from 2029 to 1995. Sarah Connor destroys Cyberdyne systems and apparently stops Skynet. (In a deleted scene from Terminator 2, we see that Sarah lived to an old age and John became a Senator.) But we learn in Terminator 3 that Judgment Day was only delayed, until July 24, 2004. According to T3, Sarah Connor dies of cancer in 1997. John Connor dies in 2032, at the hands of another T-800.
4) The T-800 which killed John Connor is "scrubbed" and sent back in time to protect him, and a T-X is sent back to kill him and his future lieutenants. What changes as a result of this time travel is unclear: the T-800 ensures John Connor and Kate Brewster survive Judgment Day, but they were presumably going to survive it anyway. John Connor now knows that this T-800 will kill him in 2032, meaning it probably won't. And the younger John Connor has now encountered a T-X. This timeline leads into Terminator Salvation.
5) Sarah Connor doesn't die of cancer in 1997. Instead, she's still alive in 1999, when a T-888 (Cromartie) comes back to kill John, and another one (Cameron) comes back to protect him. The Terminator known as Cameron jumps the Connors forward in time to 2007, and Cameron informs Sarah she would have died of cancer in 2005. Judgment Day: unknown, but later than 2010, because the Terminator known as Myron Stark is sent to kill the governor of California in 2010.
6) Derek Reese, brother of Kyle, travels back in time with a whole squad of resistance fighters. They seem to make a number of changes in the timeline, but most notably Derek kills Andy Goode, creator of an A.I. that might become Skynet. From the glimpses of Derek's version of 2029, Skynet may no longer be on the "verge of defeat" as it was in the original timeline. Judgment Day is now April 21, 2011.
7) Various other Terminators travel back in time, including Carter, who guards a warehouse full of coltan, Vick, who marries an L.A. city planner, and Myron Stark, who travels back to the 1920s by mistake. There's no telling what changes to the timeline these Terminators, in particular, make.
8) A T-1001 travels back in time to around 2005, and kills Catherine Weaver, the CEO of Zeira Corp, and her husband. It then impersonates Catherine Weaver. What changes does she make to the timeline? It's not entirely clear yet. She buys Andy Goode's A.I., "The Turk," preventing it from falling into the hands of the Connors. She saves a nuclear power plant that's crucial to Skynet's future operations, and later she destroys an entire factory that's creating prototype Hunter-Killers. She seems to be nurturing the "Turk" into becoming a more compassionate version of Skynet, but her real agenda remains unclear. Judgment Day: unknown.
9) Jesse Flores and Riley Dawson travel back from the future (possibly later than 2029.) The future Jesse comes from is much darker than the one Derek comes from, perhaps as a result of either Derek's actions, or Cameron's. We know that Jesse's future is - at least partly - one Derek helped to create, because Jesse doesn't know "Billy Wisher," aka Andy Goode, the guy whom Derek killed in 2007. In Jesse's timeline, John Connor's resistance is heavily dependent on scrubbed Terminators, to the point where there's "metal everywhere these days. Connor's got one in every major base." Sometimes the scrubbed Terminators go wrong and kill people. And the Terminators seem to be running Connor's war effort to a large extent, keeping secrets from Connor's human lieutenants. Skynet's human agents (like Charles Fisher) commonly torture humans, like Derek Reese. And there seems to be another "faction" of Terminators, which aren't on Skynet's side but also aren't on the humans'. Jesse won't say when her Judgment Day happens, but it's implied to be sooner than April 2011, because Jesse is certain it can't be prevented.
10) In Terminator Salvation, it's 2018, and somehow Skynet is already developing the T-800, which isn't supposed to exist until 2029. And in the trailer, John Connor says "This is not the future my mother warned me about. Something has changed") According to John Connor, Skynet's defeat is even less certain than ever in this new altered timeline: "I don't know if we can win this war." It's not clear what's changed the timeline from the T2 version, but hopefully the film will explain a bit. We meet Marcus Wright, an advanced model of Terminator who has a great degree of self-awareness and believes he's human until he sees his own metal body. Marcus has the memories (and appearance, presumably) of a man who was executed in 2003, and that's his last memory before he turns up in 2018. (Rumor has it Marcus' body is donated, after his death, to something called "Project Angel," which turns him into a quasi-Terminator.) It's implied that Marcus' arrival has something to do with changing the timeline. Judgment Day: still July 24, 2004, since this movie follows on from Terminator 3.
So we showed this list to Josh Friedman, producer and creator of Terminator: The Sarah Connor Chronicles, and here's what he had to say:
Jesus Christ. I want to drink whatever you're drinking. Obviously (or maybe not obviously but it should be said) TSCC never attempted to mesh with the movies, maybe in the spirit of T/1/2 but certainly not T/3/4. We've gone off the temporal reservation lately but to some degree that IS canon: almost all expressions of the franchise have massaged dates/ages to their convenience, some more than others. The most controversial idea you have in here is the first one: the "pre-Kyle" Johnfather. I believe the Terminator mythology supports that concept but many die hards just embrace the loop-ness of John sending back his dad to impregnate his mom. Of course, a pre-Kyle Johnfather calls into question genetic differences in the two Johns and whether or not Sarah's influence is the key to John v.2. If you go with the pre-Kyle Johnfather theory, the first John managed to become John Connor without her help.
Or did he?
I've mulled it over some more, and I still believe there has to be a timeline where someone other than Kyle Reese is John Connor's father. When The Terminator was a standalone movie, you could read it either way. Either there's a circular causality, where Kyle is "always" John Connor's father, or Kyle's time travel creates a new branch. But Terminator 2 pretty much establishes that time travel always creates new branches, because there's no fate but what we make. And the Connors, with their friendly T-800, are able to stop or at least delay Skynet. But of course, your mileage, even backwards and forwards through time, may vary.