Hello there, MichaelO86.

While the option to set terms a period after the end of the month is unavailable, you'll want to manually set the due dates when creating supplier transactions. I took note of your feedback and will add it to one of our future updates. To keep posted on what's new with QuickBooks Online, you can visit our QuickBooks Blog. 

Always know the Community is open and ready to help you with any questions you have. Take care and have a great day!