This is my experience in Texas with Real Estate Loans. Once a contract is accepted the seller is supposed to move out by the day the loan funds. It is important that you do a final walk through prior to closing on your home. This way you can make sure that the condtion of the home did not change during the time of the contract.
If the seller is planning on moving after the loan funds (days or weeks) the new buyer is able to charge them prorated rent for the days that they are there. Most lenders require that the buyer move into the property no more than 30 days after the loan funds. Make sure that the terms and agreements are written out as part of the contract. Do not take anyones word when dealing with real estate. Hope this helps.