20 minutes. Ad bids will take effect immediately after they are set, but due to the lag in Amazon system updates, it generally takes about 20 minutes to update.

That is to say, if you bid high at the beginning and then lower the bid later, the ad position will not change immediately after the adjustment, but the deduction will be immediately based on the new bid; if you raise the bid from low to high, the ad position will not immediately move from the back to the front.