In 2026, transfers from American Express Membership Rewards to British Airways Executive Club (Avios) are typically instant. For the vast majority of users, once you hit the "confirm" button on the Amex website or app, the Avios will be available in your BA account immediately, allowing for real-time booking of reward flights. However, there are a few technical caveats: if it is your very first time linking your Amex and British Airways accounts, the verification process can add a delay of up to 3 to 5 working days. Additionally, while the transfer is generally instant, some other Avios-based partners like Iberia Plus or Qatar Airways Privilege Club can take anywhere from a few hours to 48 hours to complete the sync. To ensure a smooth "instant" experience, it is highly recommended to link your accounts at least a week before you actually need to book a flight. If the points don't appear within an hour, it usually indicates a name mismatch between the two accounts that requires a call to Amex customer service to resolve.