Part of your agreement should be a payment plan.
With a transfer, most will require full payment, because transferring is an irreversible transaction. But you're transferring to another owner and they'll understand the need for advance payment.
For a rental, unless you are borrowing the points or otherwise putting yourself in a "distressed points" scenario, there is no risk in waiting a short period for payment. Most use some % of initial payment after the renter receives confirmation, with the balance due well in advance of the ressie. If something falls through, you should be able to just cancel the ressie without penalty. Obviously, use year, banking deadlines, and perhaps 11/7 month windows would be considerations in determining when you needed to have full payment.
ETA: It's not part of your question, but another thing that should be in your agreement is the protocol for what happens if the renter's plans change. The renter needs to clearly understand that this is NOT a hotel ressie and they probably will have very limited options (if any) if their plans change.