Quick answer

When you transfer American Express Membership Rewards points to Delta SkyMiles, the miles usually post to your Delta account within 24 to 48 hours after you confirm the transfer in your Amex account.

If you’re asking specifically about a transfer bonus (e.g., “30% bonus” or “25,000 bonus miles” promotions), the bonus miles typically do not appear immediately. They often post several weeks later , commonly in the 6–8 week window after you complete the qualifying transfer and meet the promo terms.

How the transfer itself works

  • You initiate the transfer from your Amex Membership Rewards portal → “Transfer Points” → choose Delta SkyMiles.
  • Transfers are 1:1 (1 MR point = 1 SkyMile), with minimums (often 1,000 points, in set increments).
  • Under normal conditions, people report seeing the miles in their Delta account within 1–2 days , sometimes faster, sometimes up to a few days depending on system load.

So for the base transfer : expect it within 24–48 hours in most cases.

When do transfer bonus miles appear?

Transfer bonuses are separate, promotion-specific credits. The timing depends on the specific offer, but patterns from past Amex–Delta promos are consistent:

  • The base miles (the amount you transferred) post first, within the usual 24–48 hours.
  • The bonus miles (e.g., “get 30% extra” or “25k bonus miles”) are processed after the promotion period or after verification, and commonly appear:
    • 6–8 weeks after the transfer , or
    • 6–8 weeks after the promotion ends , depending on the exact terms.

Historical forum discussions and points blogs note that bonus miles are not instant ; they’re treated like a separate rebate/award that posts later.

If you’re in an active promo right now, the exact timing should be spelled out in the offer’s Terms & Conditions (look for language like “bonus miles will be credited within X weeks after qualifying transfer” or “after promotion ends”).

What to do if your bonus hasn’t shown up

If it’s been longer than the stated window (or more than ~8 weeks with no update):

  1. Check the promo terms again for the exact crediting window.
  2. Confirm that:
    • You registered for the promo (if required).
    • Your SkyMiles number on the transfer matches the one on your promo registration.
    • You met the minimum transfer amount and any other conditions.
  3. If everything looks correct and it’s past the stated timeline:
    • Contact American Express Membership Rewards service and reference the promotion.
    • If needed, also contact Delta SkyMiles customer service with your transfer confirmation and promo details.

TL;DR

  • Regular transfer : usually appears in your Delta account in 24–48 hours.
  • Transfer bonus miles : typically post weeks later , often in the 6–8 week range after the transfer or promotion end, not instantly.

Information gathered from public forums or data available on the internet and portrayed here.