Originally Posted by
Happy
You do not need to confirm bonus - the letter is the only thing that matters.
The other thing which is a sure indication (but it typically can be seen only after the letter should have arrived) is after you activate the card and link it on your Citi AA online account, if it shows the progress "clock" towards the bonus ($3000 spend to go, NN days left) when you go to see AA miles detail for the new card.