Great question.  A conversation with the submitter revealed some additional information that made the question easier to answer.

We start at: FAR 9.306 Solicitations containing a testing and approval requirement shall-

In reviewing FAR 9.306(e) and FAR 9.306(f)(1) in conjunction with the information provided; it appears the solicitation set the delivery schedule for the first article to coincide (“be the same”) as the delivery schedule of the production units.  Not uncommon as the first article will basically be used as the specification for the production lots.

FAR 9.301 Approval, as used in this subpart, means the contracting officer’s written notification to the contractor accepting the test results of the first article. (bold italics added for emphasis).

In this case, the contractor can commence with production upon “approval” of the first article, it does not have to wait until the first article is “accepted” in accordance with the Inspection Clause of the contract.  The contract has progress payments so costs incurred in development, production, and testing (52.209-3 First Article Approval-Contractor Testing) can be liquidated at the progress payment rate.

In conclusion, the DD 250 accepting the first article does not need to be done until the government conducts “acceptance” at the end of production (again, how Section F was written in the solicitation and resulting contract).