if this is the Payment Term when should invoice become Due? on the creation? or 30 days? TERMS 50% Down / 50% Net 30 DAYS TILL NET DUE 30 % DISCOUNT   DAYS TILL DISCOUNT EXPIRES

Think you should ask whatever genius came up with that term how they expect it to be implemented.

they want system to calculate either as Net 30 because of Days till Net Due, or until 50% of the current invoice is made it is due now, and then Net 30

You could potentially use installments, but I'm not a fan of the functionality

hmm need to do more digging on that