Amazon Handling Times

You can add increase the default handling time (despatch estimate) for each product so that you do not get marked down for late despatch performance if some or all items take longer than 1 business day to despatch.
 

You can do this individually by editing each product and click the pricing and size tab then increase the handling time to the desired amount of days:

Or you can upload in bulk and just populate the SKU & handling time columns on the product upload template (download new template from products > extras > upload products)

Save the file and then re-upload it