From the viewpoint of the IRS, what you need is a binding contract
prior to August 16 2022.
What is a binding contract? This what the IRS says verbatim. (Plug-In Electric Vehicle Credit IRC 30 and IRC 30D | Internal Revenue Service
In general, a written contract is binding if it is enforceable under State law and does not limit damages to a specified amount (for example, by use of a liquidated damages provision or the forfeiture of a deposit). While the enforceability of a contract under State law is a facts-and-circumstances determination to be made under relevant State law, if a customer has made a significant non-refundable deposit or down payment, it is an indication of a binding contract. For tax purposes in general, a contract provision that limits damages to an amount equal to at least 5 percent of the total contract price is not treated as limiting damages to a specified amount. For example, if a customer has made a non-refundable deposit or down payment of 5 percent of the total contract price, it is an indication of a binding contract. A contract is binding even if subject to a condition, as long as the condition is not within the control of either party. A contract will continue to be binding if the parties make insubstantial changes in its terms and conditions.