@Samson10
To pay in advance, please follow the steps below.
1. Go to the Trip overview
2. Click on the penthouse picture, which should take you to the itinerary page/home reservation.
3. Scroll down and click the "Get receipts and manage payments"
4. Then click "Update payment details"
5. Select the "Pay ahead of schedule: Now"
Great find. I'm guessing that maybe you found this as a guest?
As a host, two weeks ago I contacted Airbnb CS via Help on a Guest booking on behalf of a guest to enable them to make an early payment. CS said "Because of the highly automated Airbnb system it is not possible to make an early payment."
Thanks for your 'help' Airbnb CS.