You will find options to manage your shipping time and order minimums within your Maker Profile page. Within your maker portal, navigate to the "My Storefront" tab and click "My Account" on the left side of your screen.
At the bottom of the Description tab on this page, you will find the Extra & Minimum Order Amount section, where you can make changes to these options.
It is advisable you provide a good cushion of time to allow for your goods to arrive within the timeframe you have given.