Please ask your administration to 7.6.6 Set up Flexible Payment Plans (FPP) before this feature is working for you (Version 2.81 and up). Currently ADvendio supports the following two use cases. If theoretically both cases could apply the selected publication date (case 1) will will over the second case. 

1. Use Case: One Invoice for each Publication Date

Here are the steps you have to follow:

1. Create your media campaign and
2. add the campaign line items you like to sell. 
3. Enter Selected Publication Dates using the new Media Configuration
   
4. Save your campaign items.
5. You will find the newly created flexible payment plan records in the related list of each campaign item:
   
   

2. Use Case: Invoice fully at the End of the Run-Time

Here are the steps you have to follow:

1. Create your media campaign and
2. add the campaign line items you like to sell and set the checkbox: "Invoice at the end of runtime".
   
3. Save your campaign items.
4. You will find the newly created flexible payment plan record in the related list of each campaign item.