15 minutes is the standard time needed for any changes made on listings to be fully processed.

However, in case that you don’t have the listing control, you may never see the content which you submitted being added into the listing.

If you don’t have the listing control, the only way how to make Amazon accept your changes is to open a case with the Seller Support under “Products and Inventory” - “Product page issue” and “Fix a product page”.

You will be asked to provide some proof supporting your desired updates, such as a link to the manufacturer’s website.