The seller agrees to deliver possession and keys to the buyer at Close of Escrow (COE) unless another date is indicated. Both buyer and seller should be aware of the liabilities that transfer when doing a pre-possession which is when the buyer takes possession prior to escrow closing or post-possession which is when the seller is still in possession of the home after close of escrow.
You should not act upon a pre-possession or post-possession agreement without seeking independent tax, insurance, and legal counsel. If you desire legal, tax or other professional advice, please contact your attorney, tax adviser or other professional consultant. A realtor is not license to advise on this matter.