Week one: prove the output
Do not begin with a giant cleanup spreadsheet. Start with enough invoices to generate a starter packet and reveal what is missing.
That packet creates the motivation and structure for the rest of the cleanup.
Weeks two and three: critical systems first
Process fire, HVAC, roof, elevator, plumbing, and electrical documents before minor repair receipts.
Ask vendors for missing certificates or reports while the gap list is clear.
Week four: install the habit
The cleanup only sticks if new invoices enter the system as they arrive.
Forwarding or uploading invoices should become the maintenance history habit, not a quarterly archaeology project.