I recently got 3 cards and I figured they would show in Credit Karma soon. I noticed today my score went WAY up, and it was due to one of the cards (CK Scores are worthless but that's another story).
I was curious which reported I knew from past experience it wasn't Discover as they take months to post. It was Barclays. Check out what I saw:
Notice the date opened? I would have been 4 years old if that were true.
No wonder I got such a boost! Isn't that a hoot?