The keys should be delivered to the buyer once the title is transferred and recorded at the county office. Many times the buyers lender funds the loan, but there is not transfer of keys until the transfer of the deed is recorded.
A lot of times buyers ask to get the keys early (prior to the close of escrow), so they can move their furniture in.
Agents and brokers frown upon this because of liability issues. The buyer’s home owners insurance does not take effect until the title on the home has been recorded.
If an accident happened while the buyer or his friends/family were moving items in the house, the sellers and their insurance would be held liable.
If the listing agent gives the keys to the buyer’s agent prior to the closing, the buyer’s agent has a fiduciary obligation to hold the keys until the escrow closes. Failure to do so could result in fines or disciplinary action to the buyer’s agent.