The time you need to move will be stipulated in the selling contract.
If you do need time to move out of your house after selling it be sure to put that in the contract.
90 days is the most you can stay in your house after selling it so you'll need to be prepared to have everything moved out within 90 days of the buyer closing on the house.
After someone buys your home you should start getting things moved out by the next day so it won't take very long to move things out.