A tenancy timeline is a dated log of what happened at a unit
Move-ins and move-outs. Inspections. Maintenance visits. Complaints, notices, and the notes you would otherwise text yourself. Each one dated, attached to a unit, with photos or documents where they exist.
It is the answer to "when did that happen", asked months or years later by someone who is not on your side.
Why it beats memory
At a landlord-tenant board or in small claims, the question is rarely what you remember. It is what you can show. A dated entry with a photo attached is evidence. A confident recollection is not.
The asymmetry matters: your tenant is describing one tenancy they lived through. You are describing one of several you managed. Their memory is better than yours, and a timeline is how you close that gap.
What to log, and what to skip
Log anything you might have to prove: the condition at move-in, an inspection, a repair you paid for, damage you found, a notice you served, a complaint you received.
Skip the running commentary. A timeline padded with routine notes is harder to read under pressure, and the entries that matter get buried. If you would not show it to an adjudicator, it probably does not need to be an event.
Photos are the part people skip
Move-in and move-out photos decide deposit disputes more often than anything else in the file. They are also the entries landlords most often mean to take and never file anywhere findable.
An undated photo in your camera roll is weak. The same photo attached to a dated move-in event, on a specific unit, is close to unarguable.
How it relates to the rest of your records
The lease says what was agreed. The rent ledger says what was paid. The timeline says what happened. Together they cover almost every question a dispute can raise, and each one is weaker alone.
Between them they also answer the questions someone else asks about your tenant. A former tenant asking for a reference needs the dates, the rent and the payment history, which is what the timeline, the lease and the ledger hold between them: the free landlord reference letter template turns those into a letter you can sign.
In UnitDocs
Open Events, click Add Event, pick a type or leave it as a note, set the date, select the property, unit and lease where relevant, write a short description, and attach photos or documents. The event then appears on that unit's timeline in date order.