Start with the evidence
Gather the relevant dates and source descriptions: when work occurred, when the document was issued and when related activity appeared. Keep those facts separate from any proposed treatment.
Work through the example
Work completed on 30 September is invoiced on 2 October. The preparation task is to present those dates and the agreement clearly, not choose a period by whichever date is easiest to find.
Make the next step clear
Send the specific question to the responsible reviewer and retain their decision with the evidence. Avoid silently moving source dates to make the working file fit an assumed answer.
Keep the source context
Keep the review period, source set and unresolved questions explicit. A checklist records work performed; it does not by itself establish that financial statements are complete or compliant. Use the appropriate reviewer for decisions about accounting treatment.