Invoice Pay Dates?

So I'm trying to figure out a formula for invoice pay periods. Attached is the pay schedule I have been tasked with using, and an excerpt from the spreadsheet I need to place the formula in. I need to use both A and B to try and find C. If B is a later date than A then I know I need to use B to find C. But if A is a later date than B, I need to be using A to find C. Another part of the issue is the pay schedule. In the example spreadsheet I've attached I've put in some example dates. Lets say the due date is 10/9/2018, the pay date is 10/17/18, but if the Due date is 10/11/18, the pay date is 11/1/18. So I'm trying to find a formula that takes that into account as well.

Any help that you guys are able to provide I would be so grateful! Thank you.

Please do not post duplicate threads, continue on the same 1 until you get resolution

I will close this 1 now, you can continue on the other 1