If you think about it, Judgment Day is inevitable. The longer it's delayed, the easier it becomes. Not only because the machines will be technologically superior to kick start things, but because humans will be more and more dependent on electronics.
I agree on electronic dependency, but not so much on the point that all delay would be easier. If Skynet is supposed to be incredibly intelligent, it should develop things (like time travel) faster than humans ever could.
There's also other factors like reduction of nuclear arsenals and increase in population against them.