Say what is late and what is complete
Give a concrete status, not almost done. Name the unfinished pieces, quality or approval risks, and every team or customer dependency that may move.
Offer options, not a hopeful date
Propose a realistic completion date and, when possible, a reduced scope or staged delivery. Ask the owner to confirm which tradeoff protects the larger goal.
Change how the next delay is surfaced
Explain the trigger that will make you escalate earlier next time, such as a blocked dependency, scope change, or percentage of time elapsed. Communication is part of delivery.