Inventory the originals first and identify gaps, while coordinating work that can proceed accurately. Do not ask a translator to reconstruct missing content from memory.
Allow time to reconcile the completed pair
Check that names, amounts and dates correspond before relying on the translated evidence. A late translation does not automatically extend an official filing or response deadline; track the actual deadline separately. Sequence the language work against the deadline that actually binds, and keep the two calendars visibly separate.
Hypothetical example: translation starts on the documents already in hand while two years of bank statements are still being retrieved from an institution that answers slowly, and the completed translation later has to be reopened, re-certified and re-paginated once the missing years arrive. Splitting the work that way costs more than waiting a fortnight for a complete set. Build the schedule backwards from the date a response is due, allow a defined window for reading the pair side by side, and treat any gap found in that window as a task with an owner rather than as a note.
A translator's availability is not a reason to move an official deadline, and a petition to remove conditions is generally filed in the ninety days before its own anniversary date, so the language work for that stage belongs on the schedule from the start rather than being remembered at the end.