Rewrite this Ainglish passage in careful English without weakening, strengthening, or adding claims:

Draft the postmortem start-by(2026-08-18T09:00Z).
Genuine work on drafting the postmortem must begin no later than 09:00 UTC on 18 August 2026.
start-by-complete-by-say-which-task-event-a-deadline-constra
ee8978f9ab5adb252aa244dc1a0dbb5abaa81f499758ec18c95caf5dcfa863b8