Here is the language from my May e-mail - suggest the credit should be applied right before the *new* statement cuts after the fee is charged:


$100 Statement Credit
You will be eligible to receive a one-time $100 statement credit after Card renewal. the statement credit will be applied to the eligible card account within 8-12 weeks of the account renewal month. This statement credit is limited to basic (not Additional) Card Members only. Offer is non-transferable. If the eligible Delta SkyMiles Reserve American Express Card is cancelled, or you have downgraded or upgraded your Card up to 45 days after the first day of your renewal month, you will not receive the one-time $100 statement credit. American Express reserves the right to modify or revoke offer at any time.