I have guests contact me rather frequently wondering how to pay the balance, when to pay, or wanting to go ahead and pay in full. I am not sure why Airbnb does not have an option to pay in full early. Having never used Airbnb on the guest side, I have no idea what is communicated to guests.
When they rolled out the payment plan some time ago, I was never informed of its inception. I only discovered it when guests started asking about it. It would be nice to know as an owner which guests are paid in full and which are not.
I always explain to guests when asked that about 10 days before check in their card on file will be billed the balance due. This is how customer service explained it to me. I do not know if this has changed.