I bought an app about an hour after I had updated my itunes account with a new credit card, but the charge went to my old card. does it take this long to go into effect?
It should have updated pretty much immediately. The new card's details were accepted by iTunes, and if you log into your account and view the payment details screen the new card's details are shown ? And you aren't a member of family sharing, and the old card isn't on the family organiser's account ?
You could try contacting iTunes Support and see if they can move the charge from the old card to the new card : http://www.apple.com/support/itunes/contact/
I updated my iTunes account with a new credit card, but my charges are still being billed to my old card
