If I didn't pay taxes there, I don't count it as a residence.

And as some one else said, I keep a copy of the last resume that I had to figure all of it out for. As for figuring it out the first time - check your memory for things that go together. IE: "I must have moved in there in July because I remember going to that festival while I was unpacking". Or "It was snowing, so it had to be in winter". Usually close is good enough for employment applications.