According the GAR Purchase and Sale Agreement, this is how closing works.

Date of Closing and Transfer of Possession.
A. Date of Closing: This transaction shall be closed on the date of ___________________ or on such other date as may be agreed to in writing by the parties.
B. Right to Unilaterally Extend Closing Date: Buyer or Seller may unilaterally extend the closing date for 7 (seven) days upon notice to the other party given prior to or on the date of closing if: (1) Seller cannot satisfy valid title objections (except for liens, judgments, and deeds to secure debt that can be satisfied through the payment of money or by bonding off the same); or (2) Buyer’s mortgage lender, if any, (including in “all cash” transactions) or the closing attorney cannot fulfill their respective obligations by the date of closing due to no fault of Buyer. In such event, Buyer and Seller consent to the closing attorney and/or any such mortgage lender disclosing to the parties and their Brokers the basis for the delay. The exercise of the right to unilaterally extend the closing date by either party shall cause the right to unilaterally extend the closing date to terminate and no longer be a part of this Agreement.
C. Possession: Buyer agrees to allow Seller to retain possession of Property until and through: [Select section 1, 2 or 3 below. The sections not marked shall not be a part of this Agreement.]
1. the closing; OR 2. _____ hours after the closing; OR 3. _____ days after the closing at _____ o’clock _____.m.

The way the contract is written - you are going to close on a certain date. If you can not close on that date, you must agree in writing with the seller before the close date. If your lender can not get your package ready, you can give one extension to the seller without their approval for 7 days. The seller can do the same if the title is not clear before closing.

Possession time is customary in Georgia. In past contracts it actually allowed 7 days and was preprinted in the contract. Now, it is agreed to. During this time, the seller does not pay rent. Remember however that the contract survives closing so they are not allowed to damage the property without consequences.