Before
At least 3 business days before, the title company will send final settlement numbers for approval.
Tour the home just before closing to ensure no damage has occurred since your last visit and before you take responsibility.
Inventory all codes, remotes, fobs, etc. for security systems, garage doors, fans, cameras, elevators, etc.
Get mailbox number (if Cluster Mailbox system) and any special instructions on how to acquire the key. Usually, showing the local postmaster a signed closing statement is all that's needed.
Locate the trash, recycle, compost bins.
Ask if any extra paint/flooring/etc will be left behind.
Ask for names and numbers of any services that can be passed along such as lawn, pool, cleaning, etc.
During
At the title company, the escrow officer will explain and notarize the final closing statement as well as all related county and lender (if any) documents.
Although most buyers wait for the escrow officer to explain the closing docs at the title office, you can request a digital copy in advance if you want to review and prepare questions.
You'll need to bring a copy of your current driver's license or government ID. Although traditional agents are often present at this event, it's purely ceremonial once the numbers are locked.