1. Log in to your Merchant Center and navigate to the "Settings" tab
2. Click "Customization" on the left-hand menu
3. Click "Edit Send Limit" next to "Automatic send delay is on"
4. Click "Automatically" and choose "Manually" from the drop-down menu that appears
5. Choose the amount of time you would like to wait before sending the first automated campaign to each new contact from the new drop-down menu that appears
6. Click "Update Delay" to save your changes